Google Adwords Error 403 Forbidden

Using Google Adwords you receive the message:

403 Forbidden

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.

We apologize for the inconvenience, and hope we'll see you again on Google.

It appears Google will display this message if make too many "hits" from your computer (your ip) to their servers. First you should make sure you have no spyware or viruses. This is not very likely...

The problem for me was that I had disabled the cache in Firefox.

To resolve this delete your google cookies, re-enable the cache and reconnect to Adwords.