Random Hangs and Freezes

[amzo at hush.com]

Well I currently have two problems, but I think they're related. 
The first one is, my system locks up when I switch TTYs then switch 
back to X. 
The other one is when playing games, such as Warzone2100, 
ExtremeTuxRacer or 
pretty much any game, I always get random few seconds hangs, 
but the music and game still continues in the background. 
I didn't suffer from this on Linux.

Though, this is only with games, 
it doesn't happen when watching movies. 
Currently I am using the /usr/ports/x11/nvidia-driver-173 for my 
Nvidia card, 
which is a Geforce FX5200 as I'm thinking this is the most likely 
candidate, 
but not sure where to start to debug it.

Let me know what information you may need.