The multiple partitions theory was something I'd been thinking for several days as it is the usual cause of the os.rename error but couldn't understand why it would be the case. Coincidently, I built a version late last night that uses shutil.move instead that I've been testing but should, theoretically, solve the issue. I didn't really want to do so until I'd determined why there was an issue on one n900 but not another. It is probably better this way for handling specialised setups like yours.

I transferred some newly ripped albums earlier this evening and added album art with this new version without any issue. I'm still getting some small disc/dots/blanks in some searches so that needs solving at some stage. The error handling, although a little better, is also in need of some work.

When I get back to laptop, probably tomorrow morning, I'll upload this one for you to test.

Incidentally, is there not anything under .cache that you would want encrypted? Tracker databases??

Edit: Had to wait for PS4 to update so here's latest test build