Have you added any programs lately? Go to the Control Panel and Add\Remove applet to see what programs are there. Any that you don't know, you should research to see if they are necessary to Windows or are used by you.
Make sure that there isn'ta lot of stuff loading at start up. Are there many icons in the Systray by the time, lower right in task bar? If so, look for options within those programs in order to take them out of starting automatically, temporarily cut and paste them to a tempfolder out of the Start, Programs, Startup menu if any are listed there. Common programs that don't need to start up are AOL and Real Player. Spy or Ad ware that could be there are Gator, Web Shots, Bonzai Buddy--these should be uninstalled. MSCONFIG is another way to check start up programs and trouble shoot your problem(s) as well as using CTRL+ALT+DEL once to see exactly what's loading at boot. Search for the programs listed by Start, Search or Find, Files & Folders and search for the names like: "name*.*" without the quotes. Right click on the found files to get an idea of what they are.
Files that should be running are Explorer (which is Windows) and Systray and possibly any antivirus.
Errors in Windows Explorer could be corruption of your Windows Installation and you can fix that by using your Windows 98 CD to do a Repair installation on top of what's there. Go to Windows update site and download and install or repair your Internet Explorer (I know it's not Windows Explorer, but this really helps many times). Best version per most people is 5.5, but 6 with latest service packs is ok by me--6 with no service packs had problems.
Remember to re-boot after repairs and installs.
Hope this helps!
