The game close while im playing

While im play Cross Fire... i can play one round of the game withouth problems... but when i start a second round... i try to do one shoot, and the game inmediatly is closed... and Ask me to send a report... Try to play again and happens the same.

MS Windows XP Professional(SP3)
AMD ATHLON 64 X2 Dual Core Procesor 4000+, 1.0 GB RAM, NVIDIA GeForce 8400 GS

Thanks for the Help