Mac vs. Windows: mystery of using keys to move instances

[brixtoncat]

I've recently been working on a game I'm making as my Major Project for the Masters course I'm in. The computer lab in the college has only Windows 2000 machines, while my computer at home is a Mac running on OSX. I have run in to very few, if any, issues regarding cross platform differences in Flash MX & Flash player until now:

I've noticed that if running a .swf file on my Mac which uses the arrow keys to move an instance on the stage, it doesn't work, while the exact same files work perfectly on Windows. On finding that my own .swf files didn't work, I went on a mad hunt to find other flash sites/games that use this technique - only to discover that they didn't work either.

Does anyone know why this problem occurs? and is there any way to work around it? I'd really like to use this function in my game, but I don't want the game to be limited to Windows-only users.

Thanks - Jessie