How to Stop a Hung File Copy in OSX

This happens rarely.  In the most recent case my girlfriend was backing up her computer to mine over the wireless network.  I'm not sure what the events were after that, but I was left with a hung file copy dialog box on my machine for days.  Relaunching the Finder seems to be a safe way to get rid of it without hurting anything.  I hope.   Apple Menu -> Force Quit->Finder.  Hit relaunch.