Twice today during work -- from the confines of Google Chrome, no less -- I've been prompted, while logged into Google, with a denial-of-service notice stating the following:
We're sorry, but your query looks similar to automated requests from a computer virus or spyware application. To protect our users, we can't process your request right now.
We'll restore your access as quickly as possible, so try again soon. In the meantime, if you suspect that your computer or network has been infected, you might want to run a virus checker or spyware remover to make sure that your systems are free of viruses and other spurious software.
If you're continually receiving this error, you may be able to resolve the problem by deleting your Google cookie and revisiting Google. For browser-specific instructions, please consult your browser's online support center.
If your entire network is affected, more information is available in the Google Web Search Help Center.
We apologize for the inconvenience, and hope we'll see you again on Google.
Just to test, I googled the terms "stuff", "oscars", and "zdnet" from my iGoogle homepage and still managed to get the prompt every time:
I know it's got instructions for deleting the cookie, but what gives?