I downloaded an avi and should have guessed something was suspicious when I couldn't preview it (even external to LW) - it kept locking up the video viewer and then windows.

When I used Sophos to scan the file for viruses, it didn't pick any up but I was viewing the files scanned and glimpsed a file called something like just kidding ;) or i'm only kidding ;) .dat within the avi (like the avi was a folder, but it is a file of course)

I was unable to locate the *kidding*.dat in Search.

I was unable to delete the .avi as it kept saying it was in use - despite rebooting etc.

I found a program called MoveonBoot which copies, moves or deletes files before Windows reboots, therefore I was able to delete this nuisance .avi

Has anyone found these *kidding*.dat files in non-functioning avis? Are they a virus or spyware? Sophos did not pick up a virus and XoftSpy did not pick up any spyware (but I have to check the sub-folder selections in case that folder is not selected for scanning).

I thought you might find MoveonBoot helpful as I have previously had files that Windows refused to delete.

Cat.

I wonder if the extension of that file is hidden or had .avi added manually to the end of the filename.

It sounds like a useful utility. There's some others listed here Incomplete Download File won't delete at all (click on link)