Files/Directories having wrong userids and/or groupids after copying data on a disk mounted in a foreign system (e.g. Knoppix)
[EXPLANATION]
The problem is, that when copying files using 'cp', the system resolves names to IDs, but uses the IDs of the currently booted system (which was in our case Knoppix).
[SOLUTION]
...avoid using 'cp' when copying files for a system which is NOT the one booted.
)OR make sure that the IDs of the two systems match.