Help with internet? Spyware?

Hello,
First, I'm not sure if I'm in the right forum, or If I should be in software one.
Anyway, here's the deal.
I have an Dell Inspiron 1200. I connect to the internet using an Alltell phone as the modem. Until a couple of days ago, I was using IE with no problem. However, now I have been getting this page http://browser-security.microsoft.com/blocked.php?r=21.0 everytime I try to get on. I have not downloaded anything other than the updates and I wasn't on any unfamiliar websites when this started. Also, the page I keep getting wants me to buy Spyware Protect 2009 for $50, which i don't have.
I am using Firefox to access right now, but it seems very limited.
I had both Norton and AVG running, on the advise of a friend, I uninstalled the Nortan, and I still have the same problem. I have run scans and came up with these:
sheur2.acyb
install[2].exe
I have tracked down both files and deleted them and then again from the recycle bin.
I've tried doing a system restore with the same results.
I really don't want to do a full system restore, just incase it doesn't work. but that's where I'm headed.
I need my computer up and fully functional by Tuesday becuase I start a new semester of school.

quick recap.
I cannot access internet thru Microsoft
but I can using Firefox.

Any help would be greatly appreciated.
Thanks so much