I can no longer access my SD card or anything other than the root directory. File Manager just shows Bluetooth as an available system (& no other file systems), & Filebox simply crashes when it tries to start.

Connection via USB asks for the usual Mass Storage or PC Mode, but after choosing Mass Storage both my Linux & W7 computers do not show the N900 file system or the SD card as availabilities. Then, when the USB is disconnected, the "Disconnect charger to save power" message from charger-only connection comes up. Subsequent reconnections via USB to a Linux or W7 computer then only show the "Charging" message, & not the "Mass Storage/PC Mode" selection screen until a power down & re-start - then the sequence repeats.

These updates have been installed since last access via FileBox or USB:
2nd CSSU-testing update
Modrana update
Enhanced Busybox update

I think the CSSU-testing update would be most likely to cause this problem.