I also had computer problems just recently. I could not access any help sites, and Windows Update didn't work, so I installed Norton (I was using Avast), and it caught a lot of stuff, but not everything. I was being redirected for almost every link I clicked, and freezing up constantly. I emailed microsoft and they talked me through several steps and tests and finally, after a couple of days of testing and rebooting, it worked. Until the problem is fixed you should keep your computer turned off while you aren't trying to fix it to keep out remote access. One scan I did was
Windows Live OneCare safety scanner: Free online tool for PC health and safety, full service scan. I also used TDSKiller and then HiJackThis, and it worked. Good luck!