I have had this problem when uninstalling/reinstalling the firmware files for various devices.
This was due to my company desktop auto deleting any files from the C:\temp\... folder at every logoff.
To fix this I tried to uninstall the firmware, when it told me the file was missing from the folder (eg "c:\temp\~2d5t" this changes for each install) I copied the folder it was looking for. Then I went to regedit > hit F3 did a search for the folder "c:\temp\~2d5t" it found 2 items, I deleted both folders that the entries were found in. I then reinstalled the firmware, and then I was able to uninstall the software. Once you install a new firmware file (ie downgrading) then remember to delete the Vendor.xml fril from your c:\.
Please note deleting stuff from your registry is not big nor clever ;)) Be careful and do a backup.