Hi to all, I've a pc gaming problem but i'm not very technical just hoping someone can help..please.

I enjoy playing flight sim games fs2002/04 i've had the same pc for 3-4 years and had no probs... now and then when i play the game the the game just stops... the reported problem seems to lie with my graphics card ' NVIDIA Geforce2 MX/MX400 ' .
Is it a matter of upgrading, if so whats a good replacement, or is it something else?
Hope you good people can help.
Thanks Dave