Gmod Crashing

I have a problem Facepunchers. Gmod crashes every 30-50 minutes, freezing everything, and popping up an error. However, this only happenes in Multiplayer mode in Zombie survival (On 2 different ZS servers).

Screen shot of the error:

Computer specs(Althought I doubt it’s my computers problem):
Microsoft Windows XP professional version 2002 service pack 3
AMD Athlon 64 X2 Dual Core Processor 4400+
2.31 GHz, 2.00 GM of RAM
Nvidia GeForce 9500 GT

I thank you all in advance.

Don’t play on those 2 servers?