Sounds like it might be an issue with file ownership. Windows 2000 quotas are based on the owner of the file, and file ownership is altered whenever a file is moved. While a user who is not the file owner can safely move files to another location, those files should not be copied, otherwise that user will become the new owner of the files. Administrators particularly need to watch out for this little gotcha, since they can easily become the new owner of a file if, for example, they were to restore the file from a backup tape to a location other than the original directory.
This was first published in June 2003