Always a good idea to power down the device, pull the battery, hold the power key for a couple of seconds, then restart the N900.

In rescueOS with mounted maemo rootfs get the info about the last running kernelThen compare the, via 'current', linked modules directory with the content of the package from the repos.
Is a complete flashing of the fiasco image possible as a last hope? There was also some info buried deep in the forum to just flash rootfs, that could be extracted from the firmware/fiasco image. Did you ever make a backup with the built-in Backup application of your setting, contacts and stuff?