Funnily enough I didn't encounter any problems with CS lately. And I'm using Win XP, Ubuntu and Mac OS X.
Foreveryoung, try pressing the following key combination:
Shift+Ctrl+Delete, tick everything (excluding Saved Passwords if you store your passwords) and click 'Clear Private Data Now'. Than try to connect to CS once again.
RE: CS blocked for Linux user?? Any other Linux-user out there?
It seems to be the same on a Spanish keyboard.