As far as I can tell, CSC stands for Client Side Caching, and it is something to do with offline folders. So I have found it on laptops but not on desktops so far, because we have offline folders set up only for laptops. On the laptops, the c:\windows\csc folder is over 2GB in size, causing space problems on a laptop with a "small" hard disk of 6GB. The solution might be to change the offline folder settings, I am currently investigating further.