NG15SP1: "administrative priviliges" error

I'm running NG15SP1 on a Windows 7 Professional 64 bit PC - all updates installed.

 

When I first installed NG15, I did it under a different administrator account. Then I decided to align account names across 4 PCs on my LAN so I'm trying to run NG15 under a different administrator account. When I first got this problem, I uninstalled NG15 and reinstalled under the new account - no difference - same error. I have been unable to get any recovery points so I cannot restore.

 

Here's what happens when I run NG15:

 

"The current user 'MEMBERS-PC\Sys Admin' has read only priviliges and cannot make administrative changes.

 

Would you like to add priviliges for full control? Click No to continue in read only mode"

 

CLICK YES; UAC: "Allow changes?" CLICK YES

 

"ERROR: No mapping between account name and security IDs was done"

 

Click OK - error window is still there or there is an identical one right behind the first error window.

 

Click OK again - error window disappears and NG15 console opens in r/o mode.

 

Any thoughts?

 

Cheers, Joe