Helping people with computers... one answer at a time.
Google Redirect/YellowMoxie sounds like a virus. Time for some step-by-step malware cleaning of the computer.
Making sure your anti-virus program and its definition database are up-to-date is the best way to make sure that it can recognize and remove viruses.
It is very unlikely that Excel and Word files can be infected with sasser because sasser travels and infects your computer in a completely different fashion.
Viruses used to be mostly just techie/nerdy accomplishments, but of late viruses have become a booming business due to spam.
One of the earliest and most common ways that viruses propagate is by using your address book to email all your contacts. Protection is required.