An about:blank problem, I think...please help me!

Hi, everyone,

I don't know how easy this will be to solve--I'm completely stuck (although I'm only an amateur at these things, anyway). My parents' computer seems to be on its last legs. The homepage has been reset to about:blank (never a good sign) and the display cannot be changed from 16 color and 640x480. The Internet is totally inaccessible, even though my father has had our ISP make sure the computer's pinging. SpyBot, AdAware, CWShredder, PeperRemoval and HijaakThis have come up with nothing interesting. I can't find anything wrong with it, even though something obviously is. Also, I can't enclose a HT log because every time I save, I get a message telling me it's not a valid Dr. Watson file. (???)

Any help you all could give me would be greatly, greatly appreciated. I'll try to give logs of anything you need, but I can't download any new programs onto that computer (no net access).

Thank you,
Minnie