Hi Folks, I hit this unusual situtation as well on a Windows 7 pro machine, I have two .pdnBak files of which I cannot delete or take ownership. Access denied. Procexp shows no threads open that are using these files, and they are exempted both from Indexing and realtime virus protection (ThreatTrack's Vipre) I have not yet tried reboot, but will try that and update the thread. I feel like this is unlikely to resolve, but since I cannot see the actual file DACL I do not know for sure that nothing has permission to these files. However, as a member of the local admins group I find it concerning that I cannot take ownership, even as the local administrator account. I am wondering if the auto backup feature can be disabled by changing a config file in either the program files or my profile settings for the program. Many thanks!