I've had the same problem since last August (search for Otlecs), and it's still a problem for me today so I wouldn't hold your breath.

I imagine the problem is that it just doesn't happen for most people, so it's near impossible to track down.

Interestingly, in my environment, it doesn't happen with all my machines either. XP broadcasting to Vista works reliably with all keys, whereas XP to XP doesn't!

I've worked around it with a jury-rigged setup consisting of Multibox and KeyClone, but if I ever get the motivation to start playing with it again will take a look at one of the other all-in-one solutions.