GMod startup crash :'(

[AdamW95]

Hey, thought I would post this here to see if anyone on facepunch could help, I am unable to play gmod due to an engine error/crash on startup:

Lua Panic! Something went horribly wrong! [attempt to index a nil value]

I have a clean version of gmod, windows vista x64, nvidia 660 Ti (latest drivers), i5-2400, 8GB RAM...

I debugged the minidump file in visual studio and it came up with :

Call stack location:
kernel32.dll!76d1c83b()

here is crash log/minidump:- [url]http://uppit.com/8l5rxrnsbf3z/hl2_145_crash_2012_10_27T18_46_39C0.mdmp[/url]

Thanks :)