Does it happen consistently and immediately as you enter the game?
In the topic at amaranthia the problem came after several minutes of play.
In the menu, does all arrow keys work or only some of them?
I just tried plugging my PS2 to USB adapter into my computer. (So you can use PlayStation 2 controllers on the PC)
I didn't plug any controllers into the adapter.
The effect was that right and down was kept being pressed.
In the start menu I could only use the left and up arrow keys, the other two had no effect. (Well, and the mouse)
When I started a game from scratch or from a save my hero immediately moved down or to the right.
I was able to move around with the mouse if I held down both the left and up arrow.
I pulled out the PS2 to USB adapter and the problem disappeared immediately. The problem also disappeared when I plugged two joypads into the adapter.
If the symptoms I describe look like yours, then the problem is most likely due to a game pad or joy pad port giving you trouble. Have you used a gamepad for a game before? Then plugging it in may solve your problem. Otherwise you can try to somehow disable it.
I hope you'll be able to solve the problem.
*hugs*
- Zeriab