Viewer upside down? Help?

Okay so I'm usually one to use the keyboard to cam around places, but today was different. Instead of moving my view at an angle up and down by using ctrl, alt, and the up or down button, it FLIPPED my viewer upside down when I hit the down button. Of course it went right back up with the up button but has anyone else had this problem? I would relog but trader is on TE right now.

Okay.. now I realize this does this on your desktop as well, but why would it all of a sudden be doing this to the SL window when it didn't yesterday? That's what I'm trying to figure out