Malware on Mac running 10.4 won't allow Yahoo/Google search

Good morning,
I've been trying to troubleshoot my wife's older Macbook Pro running Tiger 10.4. She has the virus that doesn't allow access to yahoo and google search, using Safari or Firefox. Bing and Lycos work fine. I realize that this problem is an older one and there seem to be some answers out there, but I haven't had any success using the suggestions so far. Here is one discussion that I found on Kioskea which nailed down the issue:

https://ccm.net/forum/affich-115588-can-t-connect-to-google-or-yahoo-search

The problem is that the solutions offered seem to be Windows specific, and she doesn't have PeerGuardian installed. Is there a known remedy for this issue given my wife
s older OS? We have run numerous virus and trojan scans using Clam Xav, CCleaner, Clean My Mac and MacScan. If someone could point me to where this malware usually resides in 10.4 and how to deal with it I would be eternally indebted.

Thanks