Computer infected, cannot do anything without being redirected to spyware removal page.

My brother in-laws computer got infected and I was going to direct him to this forum, but whatever virus infected his computer won't allow him to do anything. Anytime he tries to open a program or  his browser, it redirects him to this anti-spyware pro page.  I suggested he reboot in safe mode and try to launch his anti-virus but I'd thought I'd post here first.