Originally Posted by AlienQ

PS: The error is not visible in the source code when it happens.

Its server controlled and works on a CRON job. Meaning the server was hacked by someone outside.
I would advise folks start getting together and look around, this thing has been sweeping several machines as of late.

If this is the case Thank Smokey and typical GFY surfers contacting me about a trojan. He told me what was happening and seen it a bit lately.