I don't know what you are running into. I have it unmounting all filesystems before shutdown, after backup or restore, and with this latest version it -will- give you an error if it can't unmount.

The best thing I can think of is that you have a corrupt, or semi-corrupt optfs filesystem - You seem to be the only person with this problem.

What I would like you to try is:
1. install the latest version.
2. run FSCK mode. What error(if any) does it display.

Also, if you could give me a complete run down of any and all errors you encounter, and the screens you encounter them on, I'll do my best to fix anything I can from my end.

Edit:
I'm off for now, but can anyone try out SSH mode and USB terminal mode? I can ping my n900, but ssh doesn't seem to want to work about half the time, and I can't login with my root pass.
Same with terminal. I don't know if this is a glitch, or just me not knowing how to deal with these things.