Bought a new Belkin Classic Keyboard a few weeks ago, and have had more problems with it than anything else I've ever bought.
Usually when I turn off the computer (or restart) the keyboard acts as though it's been unplugged, and after unplugging and plugging the connection back it eventually comes back to life.
Just now as I started playing GTA:VC, I plugged a controller in and it turned off the keyboard. After the plug unplug ordeal it turned back on.
USB>PS2 adapters are very common, I think I have 5. Shouldn't be too hard getting one if you don't have one. I definately agree with AmIdY, sounds more driver based than problematic keyboard.
[size=92][color=#0000FF]Hugh Hefner for President[/color][/size]