can't search using google

I have Firefox and IE installed on my pc with Google installed in both as my search engine of choice. Late last night out of nowhere, google suddenly failed to search on both Firefox and IE. I put it down to an outage of some kind and switched to Yahoo which worked fine. Tonight the same thing is happening. Further more, iv'e found that when i search for the various Google sites like docs through Yahoo and try to enter them, i can't. I also can't enter forums or blogs that are associated and use google products. Could my PC have some sort of infection? == This happened == Every time Firefox opened