I don't know if it's useful info for current on-topic problem, but I got different "unknown" behavior - after successfully connecting device in mass storage once, (and removing safely), MyDocs isn't accesible for device. No big deal - I've created script that mount it again after disconnect. Furthermore, while being connected, MMC (microSD) is accessible for *both* desktop and N900 (that is, mounted simultaneously).

I can connect it again to desktop PC, yet, only for limited amount of time. After few hours (wasn't able to detect it precisely), connecting device result in charging only - HUBS with diode lighting up doesn't show any device connected, desktop OS'es doesn't act like seeing anything, etc. I've tried many tricks with osso-usb-mass-storage-enable.sh etc, to no avail. Only restart fix this problem.

I'm perfectly sure, that nothing is accessing it, also, it isn't mounting problem - device isn't recognized as USB gadget at all.

/Estel