Windows 98 Logo

The root directory should have a file called Logo.sys. That's the Window open screen.
Logow.sys and Logos.sys are the Wait and Shutdown files that are lacated in the Windows folder.
You can find new logos on the web. Here's one site at random:

http://www.vorteximaging.freeservers.com/

If you are talking about the boot-up logo, the logo is a bitmap file, but the file name has been changed to logo.sys.

However, if you are talking about your Windows wallpaper, which is what I think you mean, this sounds like either your video resolution is set too low or it's a video card problem.

Right-click on any open area of your Windows desktop and select properties. Go to the Settings tab and try selecting at least 16-bit color and at least 800X600 screen resolution.

If these options are not available or it still looks the same after rebooting, it's a video card or driver issue. Find the driver disks for your video card and reinstall it. Either that or go to the manufacturer's website and download the latest version.

If reinstalling your drivers still don't fix it, you could have a hardware problem with your video card.