You may try: logon as local administrator, disable UAC as shown in Sage document ID 10198, restart computer, install Sage MAS 500 client again. In our case, client reinstallation, using local admin account, resolved the problem. Good luck.

First thing I would try is to right click the Sage 500 application and choose Run as Administrator (should only need to do this one time) depending on what version you are on and what version you upgraded from there are some config files that get created to help the report engine run specific reports based on compatibility.

I am pretty sure this is the type of error you get when these files are missing.  They are created When launching Sage 500 but will not tell you if it fails to run due to permissions since it only needs to run one time don't want this message showing up every time you launch since it doesn't need to run every time..  

Kevin

This worked, thank you very much!

You're Welcome!