Google 403 Error

Received when attempting to reach google homepage

[Strange]

We have seen this error across our entire network here. Basically when we go to the google homepage, we get a 403 page saying the following:

"We're sorry... But we can't process you request right now. A computer virus or spyway application is sending us automated requestes and it appears that you computer or network has been infected.

We'll restore your access as quickly as posible, so try again soon. In the meantime, you might want to run a virus checker or spyware remover to make sure that you computer is free of viruses and other spurious software."

In researching the suggestions made in the given explaination, we havn't found anything that is querying google at all. Any suggestions as to why we are receiving this message would be of great help.

Thanks,
Strange