If you have upgraded from 98 to ME you will have no problem just uninstall ME the registry will be reconfigured if not you will have to reformat your HD i should point out Microsoft will not support Windows 98 after June this year
If you go to the Ebay site you will probably be able to get a shrink-wrapped 98se quite cheaply. I got one for £25. Just make sure you get an unused one. Cynical old me thinks ME was used by MSoft as a trial run for XP and look at the problems with it (allegedly).
The Cyberscrub is software that removes deleted files from your HD when you delete files they are still left on your HD and removing them will free up disk space this may or may not be of use in your case,I run a dual boot system and have never had major problems with Windows ME but there you go.
Set up and maintained properly, ME is a rock solid OS - I run several flavours of ME without problems. This OS installation I'm typing this on was installed 15 months ago and performs faultlessly.Somehow it seems optimistic to presume all your problems would disappear by installing 98.
I totally agree with leo49. My teenage sons run ME on one of my older PCs. They are constantly installing and uninstalling games, downloading all sorts of garbage from the Web, and generally doing their best to break it.
It has run without fault like that for 18 months. No intervention required from me at all.
If you want to list your ME problems in details (perhaps in a new thread with a more appropriate title), I feel pretty sure that between us we can get things stable for you.