CS:CZ Video Problem

After I installed and reinstalled my new nvidia graphics drivers I went and played Counter Strike Condition Zero for a little bit and I noticed that on some maps when I shoot black squares show up that never have before and sometimes on the walls they show up alon with on the opposing team members.... does anyone know how I can fix this problem? this has only happened since I installed the new drivers that nvidia released... I also do have my video card overclocked to 540/1100 using coolbit.... any help is apreciated