Screen savers: Friend or foe?

Network administrators have been debating whether screen savers do more harm than good since the early days of Windows 3.0. In this Daily Drill Down, Brien Posey discusses the pros and cons of screen savers.

The question of whether screen savers do more harm than good is not a new one. Network administrators have been having this debate since the early days of Windows 3.0. However, there are some serious issues to consider when determining whether to allow screen savers in your organization. In this Daily Drill Down, I’ll address some of those issues and discuss how they can affect you.

Monitor life span
The main reason for implementing screen savers was originally to prolong the life span of computer monitors. Older types of monitors were prone to a phenomenon called image burn. Image burn occurs when the same image is left on the screen for long periods of time. This results in that portion of the screen getting hot and burning the image permanently into the screen. You can see pronounced examples of image burn on many old dumb terminals that were routinely used for the same application every single day.

Because of the expense of computer monitors in the past, screen savers were designed to prevent image burn. After a preset duration, the screen would either go blank or switch to some sort of animated display.

As time went on, though, monitors became cheaper and less prone to image burn. Many people suggest that it’s impossible to get image burn on a VGA monitor. However, it is possible to get an image burn on a VGA monitor—it just takes much longer. VGA monitors are much less prone to image burn than older types of monitors.

Another idea behind screen savers is that they can secure a workstation when the user is away from his or her desk. A user can configure the screen saver to require a password before it will turn itself off and allow access to Windows.

Although extra security is never a bad idea, screen saver passwords can be a royal pain for your technical support staff. Imagine that you’ve been called to work on a PC. You arrive only to find a password-protected screen saver, and the user is out to lunch. No one else in the office seems to know the password. In such a situation, you can either waste the rest of your day by waiting for the user to return, or you can turn off the PC and restart it.

The downside to turning off the PC is that the user will lose anything that was opened but wasn’t saved. Unfortunately, with most screen savers, you can’t see what’s opened. If the user happened to be working in a database, you could risk corrupting the database by turning off the PC. Even if the user wasn’t working in anything at all, you still run the risk of damaging Windows by turning the PC off while the screen saver is running.

If you do decide to turn off the PC, you must disable the screen saver when the PC comes back up, to keep it from turning on while you’re trying to work. You must also remember to re-enable it after completing your work. Otherwise, you’ll get a phone call from an irate user whose screen saver doesn’t work.

Processing power
Now that I’ve discussed what screen savers can do to benefit a user, it’s time to discuss the negative effects that they can have on the system. Before I do, though, it’s important to point out that the screen savers that come with Windows 98 are relatively safe. They are small in size and have been thoroughly tested to work well with Windows.

As with any other computer program, screen savers consume a certain amount of system resources. For example, it requires a certain amount of hard disk space to store the screen saver. A portion of the screen saver must also remain resident in memory. This means that it will be consuming memory and the occasional processor cycle.

As I said earlier, with many screen savers this is no big deal, because of the small size of the screen savers. However, keep in mind that there are an endless variety of screen savers available from the Internet. Because many people tend to see screen savers as a way to personalize their computer, it’s common for users to download a cool screen saver from the Web and install it on their PC. Some of these screen savers can be huge.

For example, several years ago I had a Beavis and Butthead screen saver that consumed in excess of 350 MB of hard disk space. That may not sound like a lot by today’s standards, but this was at a time when 1 GB was considered to be a lot of hard disk space. Needless to say, it’s possible that today screen savers may exist that consume even more space than that.

Another thing to think about is that Windows is a multitasking environment. Suppose that you have an application running that has to do some serious number crunching. Because the application takes so long to run, you launch the application and walk away from your desk. Now suppose that while you’re gone the screen saver starts running. If you have a big screen saver with complex animation, the screen saver will steal countless processor cycles from your business application, thus making it take much longer to complete its task.

OpenGL screen savers that do complex 3D rendering are notorious for consuming a lot of processor power. You should never run them on servers. Likewise, you should discourage users from running them on workstations that may do a lot of background processing, such as spreadsheet recalculations, real-time monitoring, or database reindexing.

DOS applications
Another issue to consider is that of DOS programs. Even though Microsoft has tried to phase out DOS, many companies still run proprietary DOS-based software. This software may consist of databases or other business applications. By default, Windows 98 allows the screen saver to come on while a user has a DOS application opened.

If the DOS program happens to run in graphical mode and the screen saver launches, Windows may have trouble returning to the application once the screen saver is turned off. This is because the graphical mode the DOS program uses isn’t native to Windows and Windows doesn’t know which mode to use. Because the program wasn’t written to be used with Windows, it doesn’t know how to communicate its graphical mode with Windows.

You can avoid this problem by right-clicking on the icon associated with a DOS program and choosing the Properties command from the context menu. When you see the shortcut’s properties sheet, go to the Misc tab. The Misc tab contains an option that you can use to prevent the screen saver from launching while the application is opened in the foreground.

General protection faults
Another issue to consider is that of general protection faults. It’s possible to write an entire book on GPFs, but generally speaking, they occur when two programs try to use the same memory space.

A screen saver by itself won’t cause a GPF. However, if you have a PC that tends to be prone to GPFs, having the screen saver running greatly increases the chances of a GPF occurring. I’ve seen screen savers (including the ones that come with Windows) trigger GPFs too many times to count.

As I mentioned earlier, downloading a cool new screen saver from the Internet is an option that’s available to almost every user. However, not all Web sites are created equally. Some of the more reputable Web sites scan all files for viruses before they are posted for download. However, many Web sites don’t offer such protection. When you download a file, you’re at the mercy of the download site’s Web administrator. The file may or may not be what the description said it was. Likewise, it may or may not contain a virus.

If you decide to allow third-party screen savers on your network, you should make sure that every PC contains an up-to-date virus checker and that the virus checker is set to download updates frequently. You should also explain to users the importance of downloading from reputable sites.

Earlier, I explained how a large screen saver that’s running on top could slow a background application to a crawl. However, a screen saver can stop some applications altogether.

One such example is the Disk Defragmenter. As you probably know, the less fragmentation that your hard disk contains, the better it will perform. Because of this, many people set up a timer to run the disk defragmenter at certain times. If the screen saver kicks on while the disk defragmenter is running, it will cause the disk defragmenter to start over. The disk defragmenter will never be able to complete its task as long as the screen saver is running.

One final issue to look at when trying to decide whether to allow screen savers is that of software licensing. Licensing is a non-issue for the screen savers that come with Windows. If you have a license for Windows, then you automatically have a license for the screen saver.

However, as an administrator, you have absolutely no way of knowing where a third-party screen saver came from. You don’t know if it’s legitimate or bootleg. You don’t know if it’s commercially copyrighted, shareware, or freeware. Even if you do have an idea of where the various screen savers came from, it could be tough to prove it if there were ever a software audit in your organization.

In this Daily Drill Down, I’ve discussed some of the many issues that a network administrator must face when trying to decide whether to allow screen savers to be put on computers within the organization. My personal opinion in this matter is that screen savers tend to cause more problems than they solve. However, this is a decision that network administrators must make on their own.

Brien M. Posey is an MCSE and works as a freelance technical writer and as a network engineer for the Department of Defense. If you’d like to contact Brien, send him an e-mail. (Because of the large volume of e-mail he receives, it's impossible for him to respond to every message. However, he does read them all.)

The authors and editors have taken care in preparation of the content contained herein, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.

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