Had all the same problems with COD4, but got a fix:
Download this file:
After doing the update from the pbsetup.run program from even balance, I added this one file to Call of Duty 4/Call of Duty 4 Data/pb/dll
IMPORTANT NOTE: it comes down as a .mac.dylib file. Rename the file removing the .dylib tag.
All is working now.
Umm i need help. So yeah you guys say run pbsetup and then do this blah blah. But for me when i click pbsetup it says i can't run the app because PowerPC is no longer supported. Anyone know how to fix this. It's really annoying because i can only get onto like 4-non pb servers which are really laggy.
This did the trick. Very easy and straightforward. Go to this link and follow instructions, in 5 minutes it's fixed.