Symptom
If you click Stop in the Copy progress dialog box while a file is being copied from the computer to the server, the dialog box may remain for a long period of time. Sometimes, the wait is so long it seems as if the computer has stopped responding.
Solution
Wait until the dialog box closes. Do not force-quit the Finder or reset the computer.
The length of time that the dialog box remains open depends upon how large a file is being copied and how early in the copy process you click Stop. Larger files and earlier stoppages result in longer waits. For example, clicking Stop when a 2 GB file begins to copy may result in a 90-second wait for the Copy progress dialog box to close.
The Finder allocates space for the entire file when the copy is started. When you click Stop, the Finder attempts to close the file so it can be deleted. However, since the entire file has not been written, Mac OS X Server writes zeros over the portion of the disk allocated to the file that the Finder did not write over. This is to prevent data on previously unused sections of the disk from being incorporated into the file. Once this zero fill has completed, the client returns to normal operation.