Browser Hijack Problem

[Mempho]

Hi,

I've had a problem with one of my computers for quite a while now. The browser has been hijacked and it does not let me go anywhere now. I have run adaware, antivirus, and spyware. These programs find the hijack application and supposedly remove it. The program just reappears, however. I have tried to delete it manually, but, once again, it reappears. Does anyone have any advice or am I just SOL on this one and have to reformat?