Looked at the P7 instal DVD and the documentation - nothing about a skinshader item in the python scripts. NB - the test was also carried out on an external HD which had been fully checked and was running Leopard, not Tiger. Will run a full suite of tests/permissions in the morning and double-check everything, but I don't think there's a permissions problem and recent Diskwarrior checks have not come up with any directory problems.

Thank you for all your interest!