trench3, thanks for your report!
COB is ClickOnce application, so there is no executable file -- its ".application" file. Thus there is no "Run as admin" option in Vista.
However COB should elevate privileges itself (asking for users' password, as "Run as Admin" does). Elevated privileges will allow COB to back up files that are open in other applications.
This will be implemented in next release.
For now, message "COB capabilities are limited. Service for copying locked files is not active. Power User privileges is required to enable it" can just be ignored.