User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b6) Gecko/20100101 Firefox/4.0b6 Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b6) Gecko/20100101 Firefox/4.0b6 After you drag a file unto Gmail and wait until the async upload has finished, Firefox keeps the handle to the dropped file open making it impossible to delete until Firefox has been closed. Reproducible: Always Steps to Reproduce: 1. Goto Gmail 2. Compose a new message 3. Drag a file from the desktop unto the drop area 4. Wait until the file has finished uploading 5. Delete the file from the desktop Actual Results: Windows will complain that Firefox has the file open for reading. Expected Results: The file should delete as usual. FF4 Beta 6, x86 build running on x64 Windows 7.