Bioshock - "Stuck key"; Can only move left

I just recently bought Bioshock from the Steam Halloween sale, and I can't even pass the "tutorial level". After I move for a bit, the game suddenly starts pushing me left, as though I'm pressing the left key. I can press right to counter it and stop all movement, but I can't move backwards or forwards. There have been a few other instances of this problem, but none with solutions. My computer is very capable of playing the game, and I've never had this problem with any of my other games. I am using a somewhat-old PS/2 keyboard, but I doubt that's the issue. Unfortunately, I don't have a USB keyboard to test and verify. Any ideas?

Just to check, do you have any other controller-type devices attached to your PC other than your keyboard + mouse?

This happens to me sometimes, not necessarily with bioshock 2 just in general. have you tried remapping the move keys? restarting the game? smashing your keyboard against something? the last one might a bit drastic but it does wonders.

Good to hear you found the fix mate. I recently bought it too and I had no dramas.