Comment 3 for bug 689516

This might be an issue related with the fact that on windows you cannot renamed files that are currently under use. Can you confirm that you did not have those files opened by any process. The easiest way I know how to do that is using Process Explorer (http://technet.microsoft.com/en-us/sysinternals/bb896653) and find a file/handler with the name of the failed downloaded file.

I fear this is an issue we cannot work around, but nevertheless I'm thinking how to work around it.