replace the hard drive with a new one.
thats the next option.

yes I agree, you can change the harddrive yourself.
as long as you have all your drivers for sound card, video card, NIC card etc.
most of them you can get new releases from the vendors.
open your...

try adaware se and spybot search and destroy 1.3.
download avg antivirus and run that.
what OS are you using? make sure its up to date.
I was having the same problems on one of my win 2000...

did you try the ram again in the other PC?
you didn't bump the CPU or install the ram backwards?
it has to be something you did when removing the ram,
or installing it back. check that stuff out...

what kind of hard drive is it?
look up the hard drive on the net and see if there is a bootible utility.
your hard drive could be failing, I have had 4 western digitals fail.
there should be...

did you delete any files?
sounds like it could be your video card.
I am going to ask a dumb question
is the monitor plugged into the computer?
I am assuming you checked that and it was.
try a...

you could also make a small partion and install win 98 on it.
boot to win 98 and change the file you want.
then delete the partion you made.