hl2.exe Crash "Sending Client Info"

Everytime I join a server and get to the second last bar of “sending client info” it decides to crash (hl2.exe has stopped working).

 You crashed in materialsystem.dll with the failure NULL_POINTER_WRITE_c0000005_materialsystem.dll!Unknown on Fri Nov 11 08:11:23.000 2011
      • Graphics card is identified as "ATI Radeon HD 5670"
      • Graphics card driver version was ""
      • Operating system is "Service Pack 1 (Build 7601) version 6.1"
      • The loaded map was "rp_evocity_v33x"
      • The command line options were "-game garrysmod -steam -dxlevel 81"
      • You were using 89 % of your memory


I found out it’s the map that’s crashing me “rp_evocity_v33x.bsp”, is there anyway to fix this?