Downloads fail at the end

Everything I've tried to download has failed right at the end of the download. I get a *.part file that looks like a complete download, but the download never completes. Download manager says that a few seconds remain, but never completes.

When I restart Firefox it tries to finish the download, but fails again. The attempted download restart has also overwritten a file that I copied to the same directory of the same name.

I'm using version 3.5

Is there a URL to file a bug for this?