Is there a folder named Temp Doc on your desktop? If not, you'll get this message.
Also, is your user account name "mmccarty"? If not, even if it's one letter different, you'll get this error message.
I recommend that your replace this expression with:
"file:" & Get ( DesktopPath ) & "Temp Doc/" & <expression for file name goes here>
I think that this file already exists in the "temp Doc" folder and FM is unable to write it over (may be it is in open state).
Check this first and if the file exists, cancel it, or try a different name.