you might also try your system restore { start/accessories/system tools}

especially if you can come close to a date when it started acting up??

save any special files to make sure you don't lose anything.

I used sys restore a couple of times when i had some major problems {lost some info} and it brought me back to where I could find the info again.
But puter had other problems{viruses}and Hrdrive eventually croaked

also use the Disk Cleanup tool if you haven't done that yet.

Mozzilla Firefox or the new Netscape 8 or 8.1? seem to be better browsers than IE.
the new Netscape has built in security features.
free to download @ mozzilla.com and netscape.com {look for download section}

you might look at trying the new linux operating systems {less viruses}
look at some of the older threads -named duel boot {should be dual boot}, linux ubuntu, ect.
You can get them quick in a Linux computer magazine $10. bucks or so
just put in the CD or DVD??make sure you get the right kind for your computers player.
you can "test" drive em by running from the CD/DVD player.
only prob I have now is the wireless connection- so use a wire until that's figured out.
or win XP why it's called dual booting- choose at boot up to use the Linux OS or windows OS.
one on sys restore too