Weapon model error

So whenever someone takes out an Ak-47 from CS:S it’s just invisible, and my console gets spammed out the ass with: Error Vertex File for ‘weapons\w_wst_ak47.mdl’ checksum 912833314 should be 1652093399.

http://cloud-2.steampowered.com/ugc/1100291843088424975/D3058A353E710AC82A3DECA9D70AA721F174E2D3/1024x576.resizedimage

I’ve reinstalled CS:S hoping that would work but to no avail. I was really wondering if someone could help me with this because it is really annoying.

Have you installed any custom CSS skins?