Counter Strike Source issue

Hi! I was recently given a copy of Counter Strike: Source from my friend for my Mac. I installed it, and ran it, and playd it once. Note: I already had Half-Life 2 installed at this point. Now, when I try to run it, the screen fades to black, then comes back (still with that blue-ish tinge Mac screens get for games) and says:

"Microsoft Visual C++ Runtime Library

Runtime Error!

Program: C:\Program Files\css\hl2.exe

This application has requested that the runtime terminate it in an unusual way. Please contact the application's support team for more information."

I figured the GameSpot community would be a good substitute for the support team (And would work a great deal faster). Note that Half-Life 2 had been installed and had been run prior to my first, and only, successful use of Counter Strike Source. Any way to fix this, or does anyone know why Half-Life is blocking Counter Strike?

Do you have any idea where I could find Microsoft C++ for Mac? A quick Google search did not seem to get the desired results. wantfastcars