At first, I tried deleting the cache, nothing.
Then I tried deleting the SH cookies, nothing.
I tried resetting the router, nothing.
Jeremy told me to use Vtunnel, I did, and it worked well but it wasn't as smooth as I wanted it to be.
I erased my HD and upgraded to Leopard, then everything was fine.
Since then, I've had one instance where I could not log-in. But I was fine after deleting every SH cookies I could find.