Partition Assistant - Information Code 43

I am trying to merge 2 partions with the Partition Assistant.  Each time I try I get the following message:

"Operation Abort.  Information Code 43.  Some files or folders cannot be accessed when enumerating a directory. Press any key to restart.

How do I determine which files or folders are the problem? How do I get fix this so I can merge the partions?

Any assistance is gratefully appreciated.