I can't play garry's mod

a couple of weaks ago my pc crashed and I can’t play garry’s mod
and i install counter strike source on a other pc.
yesterday we got our computer back and i reinstalled steam and garry’s mod.
but when i try to play multiplayer it says this:

http://img190.imageshack.us/img190/5476/garrysmodproblem.jpg

sorry the language is dutch :stuck_out_tongue:

i have removed steam on the other pc.

do you guys know what i can do
thank you

(my engish sucks i know)

Log out and back into steam.

Your English is rather good actually