If you're already right clicking and choosing to run as administrator then you must have some other application stopping it. Either an over zealous malware app or virus scanner? Something is halting the program from writeing to its cache folder.
If you figure out what it is please let us know.
You may also want to try Landiins eq2map updater. It is written differently and you may have less trouble running his application...
http://www.eq2interface.com/download...APUpdater.html