Windows 7 Explorer bug that silently aborts large file copies

Just stumbled on a pretty awful bug in Explorer. Figured I'd make a quick page about it in case other people run into it. It's easy to avoid, and also only triggered by doing something fairly unusual (for most users at least), but if you run into it you'll be unlikely to trust Explorer to copy a lot of data until you understand what triggers the problem and what to avoid doing in order to stay safe.

The bug:

If you open Explorer windows via the command line (e.g. explorer.exe /e,<path>), for some reason it opens them in separate processes. Strange, but fine so far...

Start a file copy (or move) between two such windows and then close the windows, leaving just the copy progress dialog behind.

After a minute or so one of the processes will exit, while the copy is still going, which in turn silently aborts the file copy.

There are no error messages or warning signs to tell you that the operation didn't complete, since the progress dialog simply vanishes the same as it would after a successful operation. Unless you happened to be looking at the progress percentage when the window closed, you wouldn't know anything went wrong.

Video of it happening:

Download: Win7ExplorerDataLossBug.mp4