#3 - Feb. 22, 2010, 12:25 a.m.
You should be logging into the game client the same way you did these forums, Infernoz, using your e-mail address as the account name. If you can log in with the battle.net account info on the Battle.net account site and the forums, but not on the client, then there may be a problem with the client itself. It may have been corrupted, possibly by a virus.
I would first check for any viruses. Have the login in screen open while doing this in case the virus is in the client itself.
If there is no virus found and the problem persists then I would suggest looking to our Technical Support forum for more information, they may require you do uninstall and reinstall, but I would rather you check with them first, before you proceed.