I once got a virus that shut down and uninstalled all my antivirus and antispyware, and if I went to any antivirus website to download new ones the virus would redirect me to identical sites that were in fact fake sites containing more viruses.
Gotta applaud their efforts there. Good thing I'm not stupid because I think most people would have been ****ed by that virus.
The solution was of course to identify the virus by taking note of which addresses it redirected me to, and finding a program made specifically to kill that virus. Those exist for the majority of the tough viruses around.