Reciently I was working on a computer running Windows Vista and trying to zip (compress) a file that was testing positive for a Trojan virus. A "File not found or no read permissions" error kept coming up, preventing me from zipping the file. Using other compression software like WinRAR also threw an access violation error.
The problem I determined is related to the antivirus software, in this case AVG. Traditionally right clicking the AVG icon in the system tray and selecting Quit AVG Control Center will turn off the antivirus and allow you to proceed. But in this case AVG's background heuristics scan does not shut down. To do this:
1. Press the "ctrl, alt, delete" keys at the same time and select "Start Task Manager".
2. In the task manager select the processes tab and right click any processes running thats starts with avg and select "End Process" Once AVG has been totally shut down you should be able to zip, move, copy, compress, or whatever.