Right now (I'm using 3.0.8) if DTA fails only in renaming a file to it's final name (but it otherwise succeeded in downloading the whole file) the size column states "File access error", the progress bar is set to red with a red "x" on the left, and resuming the download restarts the whole download.
A "File access error" could mean anything and for a normal user without the diagnostic log enabled the only way to tell if there was only a renaming error is to download the whole file again until it succeeds (and then compare the downloads and find out that he already managed to download the correct file).
For a renaming error you could just say "Unable to rename" and possibly color the progress bar in yellow (rather than red).
You should ensure that the temporary file does not get deleted (while most times when #63 happened to me the temporary file was left, once or twice it apparently was not - but I'm not 100% sure that it wasn't my fault).
Ideally there should be a "retry" or resume function that DOES NOT download the whole thing again, but simply retries the renaming.
Best would be to give a more extensive explanation of what happened, either in a pop-up or in the documentation, stressing that the download has been successfully completed and the user can simply rename the file by himself.
Implementing this could make much less relevant bugs like #63 / #105, when the failure is only in the renaming step (that has always been the case for me when the "File access error" occurred).
This can be regarded a part of #136.
Be specific on errors to move file
Related to #171