Software Error

I play on NoxiousNet Zombie survival server and i get this wierd message that varies such as: (The exception unknown software exception “0xo890000005” failed to write at location “Ox000dc005” click ok to terminate the program) and i would just have to reboot the game (this only happend when i played on that server and others on the server had it happen all the time but now it happens when i Launch Gmod so i can’t play it at all! i tried reinstalling it any help?
I have an AMD 64x 3800+
2Gb ddr2 4 sticks of 512mb
some sort of asus mother board
and a 9800gt
i have never had this prob before ever!!