Access denied to temp file

Has anyone seen this issue before? One of my users has reported it. Access is being denied to the temp file created by ExcelDna.

Any idea how to approach solving this? Firstly, maybe showing a better error message to the user. I have gobla exception handling in place, but I think this exception is thrown too early. A nicer message in a MessageBox to the user suggesting how to fix it would be great.

DnaCompilation [Error] There was an error in loading the add-in XXX (C:\Users\***\Downloads\xxx.xll):
DnaCompilation [Error] There were errors when compiling project:
DnaCompilation [Error] error CS0009: Die Metadatendatei 'c:\Users\***\AppData\Local\Temp\tmpE480.tmp' konnte nicht geöffnet werden -- 'Zugriff verweigert'

The last line translates to:
The metadata file 'c: \ Users \ *** \ AppData \ Local \ Temp \ tmpE480.tmp' could not be opened - 'Access Denied'