Heres the dmp file. http://dumps.garrysmod.com/?view=4055724638&refresh=16
Try changing your shader level to low, if that doesn’t work, try updating your drivers.
( Also, this isn’t just you, I have multiple reports on my forums of rp_downtown_v4c doing the same thing, some players can get in fine, others can’t. Normally the shader adjust works. )
oh lawd… u got an ATI 5700 series too, I’ve been getting a lot of screen flickering and stuff, it was probably the latest driver update it seems to be goofing up a bit