BUG You wonder what Windows 98's System File Checker does, so you decide to give it a spin. After fixing some corrupted files, you reboot, only to be greeted with multiple Windows Protection Error messages ù or no Windows at all.

Inside Windows 98's Accessories menu lies the System File Checker (to launch it, choose Start-Programs-Accessories-System Tools-System Information-Tools-System File Checker). The utility is a great idea: if your PC has problems caused by a corrupted, missing, or otherwise faulty Windows operating system file, the checker identifies it and prompts you to restore a good version of the file from the original disks. But because the program doesn't know the correct location of certain Windows system files, it sometimes copies files of the same name from the scaled-down version of the OS known as mini-Windows. Mini-Windows files are used by Windows 98 only during its initial setup.

WORKAROUND Microsoft describes the problem in brain-numbing detail at support.microsoft.com/support/kb/articles/q192/8/32.asp. To fix a Windows installation that's "gone mini", you have to boot using a Windows 98 start-up floppy with CD-ROM support, and then restore the files one by one using the extract.exe program. Microsoft offers a blow-by-blow account at support.microsoft.com/support/kb/articles/q129/6/05.asp.

- Scott Spanbauer