Stuck at Welcome screen

Today I booted up my PC and instead of loading normally as it always does, it stucks on the Welcome message on the logon screen. The loading icon keeps making circles, as if it's working but the users don't show up (I can't move the mouse). Sometimes my user appears for split seconds, as if it's trying to log in on it's own. After changing the language with a keyboard shortcut and clicking around it says Username/password wrong and I can finally log in. The only significant change I made yesterday was installing Ubuntu on a different partition, and I even removed all services and applications from msconfig, even did a system restore. Now I'm doing an in-depth scan with NOD32 to see if it finds anything.

If all else fails, do a repair install.. This will show you how to do a repair upgrade install to fix your currently installed Windows 7 and preserve your user accounts, data, programs, and system drivers.

http://www.sevenforums.com/tutorials/3413-repair-install.html?ltr=R

I did some scans and the repair afterwards, however nothing changes. Maybe not Windows, but some 3rd party software is trying to automatically log in and enters the wrong password. It's as if the password is entered automatically.

Oh well, after activating Windows after the upgrade it appears the problem was solved. Weird.