I've got some users complaining of this message when trying to upload files.  They're using the latest build of Firefox and say that the popup appears after the file progress finishes.

 

I can't reproduce the problem using the same site and same browser (or even IE7).  This has been working without issue for about 45 days now.   We're using a temp directory within the application and the files in there are all from today prefixed with "persisted" except for a couple that are prefixed with "uploading" in the name.

 

The site is load balanced and when I'm comparing the files in the temp dir, I'm noticing that the same files are on both servers.  Also, the ones that say uploading are from hours ago.

 

The site is running on Windows 2008, IIS7 (Integrated) using ASP.NET 3.5 sp1 and running under SSL.

 

Thanks,
David