Debian 6 amd64, Gnome desktop.
The logon screen appears regularly. After logon, the desktop background and mousecursor appears. Nothing else happens even after a lengthy wait (hours).
Same happens for a newly created user account, or root.
.xsession-errors only contains "beginning session setup...", and thats it. No further changes until I shutdown the system from the commandline. Then xsession complains about losing the Display.
System used to work until before my holiday. I did not change the system in a while, except for updates, and I did reboot about 3 weeks ago, did work then. System clock is correct.
How do I debug what component is hanging?