Since the CSSU-Testing update, I'm no longer able to access the N900 file system via file manager, FileBox, or Mass Storage mode connected to W7 computer.

File Manager shows just the SD Card & Bluetooth available
FileBox just shows the SD card
Mass Storage Mode > Windows Explorer doesnt show either, or bring up the "Scanning device" box, etc.

The odd thing is that I think it worked a couple of times via Mass Storage Mode > Windows Explorer, as I remember the 1st time I connected it via USB to a W7 box after the update it gave a warning that it was unable to install software for the device, specifically memtioning PC Suite.