I sorta have the same problem. I work for this school and only on this computer I am typing from do I have issues when trying to access google.com. I get a HTTP 400 Bad Request. If I go to yahoo.com, bing.com, or any page where you can "search the web" because searching the site is no problem.
I thought it was only with Internet Explorer but I downloaded Safari, Chrome, and Mozilla to see if this problem occured across the board and it does. The system I am running is
Windows XP Professional, SP3
Pentium D CPU 3GHz, 1 GB RAM
Harddisk drive 80GB
Running all sorts of browsers, now.....(Testing Purposes) - Originally just IE.
Scanned the computer for malware/adware/spyware/viruses of all sorts and nothing.
I do believe at one point there may have been a bad malware issue, which is making me think this may be reminince of that. Any direction would be greatly appreciated.
Mike H.
Computer Support Tech.