Crash to desktop when using the tab key (scoreboard)

As above. How to resolve this?

PC specs?

Specs:

Intel Core i7 920
MSI X58 Pro
GTX 285
Corsair 6GB DDR3 CL9
Andyson F650 650W PSU
Samsung 2494HS LCD

No OC at all. Running GMod at 1920x1080 max settings.