Jason is right about the space reserve.
It could be a number of things that make it crash..
It could be Deuspack.. You would have to have modified it though, because his code is pritty much flawless.
It could be programs running in the background that you didn't have before.. Believe it or not, Tribes is a mega resource eater, and it hates it if another program trys to stand in it's way
It could also be the memory buffers overloading, which from a client side, is hard to do.. Unless you have masses and Imean masses of custom scripts running.