Also, I d suggest adding some form of antikeylogger software as well. The safest option would be to wipe your system clean and install antivirues, antimalware and antikeylogger.
Do you or anyone else have any information on what antikeylogger and PC-Scanning software is reliable?
I found out there are lots of cases where people experienced the same thing as I did. Another one from only 11 days ago:
https://www.reddit.com/r/Bitcoin/comments/44azpv/successful_authorization_on_old_btce_account/Some do even go as far as to say that they suspect btc-e of selling the accounts infos etc. Because those people also did not find any keyloggers or similars on their computers.
It indeed is very weird. My PC also seems to be clean. At least according to avira and according to the fact that no other account by me got compromised. If I was infected with something they would have way more data than that BTC-e account. And in fact that would be the last account they'd obtain by me because I didn't ever use it actively and it was fully inactive for 1-2 years now.
This is very weird indeed. I can't exclude the possibility that btc-e's database is compromised or something.