Aus_Karlos

This could be an issue with the downloaded contents you got from the server. You can delete the files that where downloaded and reconnect to the server to see if it fixes the issue. (Downloaded files are found in Steam/Steamapps/User_Name/Counter-Strike Source/cstrike/ Then can be in multiple folders like Sound, Material, and Models).
Deleting these folders completely are ok even though the game requires them, however they will be re-created when the game starts again, it might take a little longer to load.

If not then can you please post your system specs and take some Sensor readings using Everest from my Sig.