I have noticed that when I am doing seperate multiple copies of large files, the buffer/clipboard is cleared when a preceeding copy finishes.
For example, if I select file A and click copy and then paste.
While this copy is in progress I then select file B and click copy, if before I click paste for file B, the file A copy finishes, the file B copy has disappearred, ie the clipboard has been cleared. I then have to re-select file b, click copy and then can paste.
I can't reproduce this either, on XP or Vista, copying between two normal directories. (I didn't try special directories like Desktop.)
Here's something to try: After Ctrl-V pasting once and waiting for the copy to finish, push Ctrl-V again. The file you just copied should still be in the clipboard and you should be asked whether you want to overwrite it.
Are you running a clipboard monitor or clipboard history program or something else which can automatically store or modify the clipboard (e.g. PureText)?
What about Remote Desktop, VNC, Synergy or something else which shares the clipboard between machines?
It's a bug. There's no setting. It has been reported to GPSoftware.
It does make sense for the clipboard to be cleared after a cut & paste if it hasn't changed since you can't paste a cut file more than once (the source no longer exists). It doesn't make sense for it to be cleared if a different file was put in the clipboard after the paste, and that's the bug.