Well it seems that the very very very clever hackers out there have found a way to get past the reCaptcha at forum registration.
I have tried changing the spam prevention measure to Q&A but it seems my simple questions like what is 1 + 1 were also not strong enough to prevent them from auto registering.
This is my latest attempt to block them. Now when a user signs up they will be asked a question about this picture. If they can answer it they are a human hopefully.
I really hope this works as it is impossible to activate new users accounts due to the sheer amount of spambot accounts.
If anyone else has any other ideas please let me know.