Even without TW, I ran into some permission issues in an office with mixed PPC/Intel Macs, mixed 10.4 and 10.5, and a network drive attached to a user workstation.
In that case, disabling permissions on the shared drive solved the problem. This of course exposes them to a accidental or malicious loss of data if someone (one of their kids even) plugs into their network and accesses that drive. So, it is not without some risk.
See attached screenshot. Do a Get Info on the shared drive and then check the box to "Ignore Ownership".
If the drive has lots of stuff on it, it might be safer to test this idea on a virgin partition with only your TW stuff. Use Disk Utility to add a partition to one of your drives, do the Ignore Ownership thing on the new partition, copy your TW files there, and then see if the problem is resolved.
Just a thought.
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB