1. Change the display settings to what they should be, then reboot. It should save them. (Have you been turning your computer off instead of shutting down properly?
2. Check Event Viewer for which DLL file it is, copy it over and see if the message goes away.
3. Defrag was NEVER good in Win98, get a program called Buzzsaw from
http://www.dirms.com/
4. Known fault - STOP USING IE, IT'S CRAP.
5. See 4.
To be honest, to get that last bit of mileage out of your hardware, get a lightweight Linux distro, your computer will be worlds more stable, faster and more secure. And you'll learn a lot.