Windows restore does not completely revert your system to the way it was. The computer is capable of reversing the changes. That is, you can un-do system restore, which demonstrates the fact that the machine has everything saved in memory, including the virus. You have to do a system restore in safe mode in order to wipe the memory, and even then, some heavy-duty viruses can survive, or even prevent you from doing a system restore in safe mode. They can even corrupt your restore points so you can't use them.

I have had viruses like yours before. After a system restore, it takes a while for it to get out and corrupt your system again. I highly doubt the fauna classifieds are causing it to come back. It's either coincidence, or there's something about that site that is cuing the virus to activate.

You may need to re-install your operating system from the install disc to completely wipe the virus out. I recommend you either do that or take it to be repaired by a professional, or somebody might be reading your keystrokes and stealing your passwords/credit card information.