Boot up your PC with a Windows 98 boot disk, pop in your Windows 98 CD, and once you're at the command prompt, type your CD-ROM drive letter immediately followed by a colon.
So, if your CD was set to "D" -- you'd enter D: and then hit ENTER.
At this point, you'll type the following command: SETUP /pf (exactly as shown).
This switch will restore all of Windows' critical files to their "factory state," and in 99% of situations,
and doing this will fix whatever problems you were having in Windows 98.