Optimizing Application PBL Failed - PB 11.5.1

Greetings All,

When Optimizing the application PBL I am getting an error message.

     Renaming of the old library to backup file failed.

     Old library is still intact. Optimize terminated.

All the other PBL's optimize with no issues.  I checked the permissions on the PBL file and the folder and they have write permissions.

Any idea's?

FYI - Using Powerbuilder 11.5.1 (build 4011) on Windows XP 32 bit

Thanks,

Tom