Ok, so my problem is persisting. I've read about the SP2 bug, tried to use setshell after a fresh reinstall before reboot, after upgrading, without luck. I'm using classical login, and it's still freezing after I log in. With File -> New Task -> explorer, it only opens up a explorer window, and doesn't start explorer as shell. I dunno if that's how it should be, or not. But it's enough to be able to change back, though.

I'll try a manual install now, but does anyone know what my problem could be?