Comment 24 for bug 218070

I had the same problem also after an upgrade to hardy.
I think I fixed it, I've done 2 thinks and I don't know which one made if finally...

1. ~/.metacity/sessions created a file named default0.ms containing following lines:

<metacity_session id="default">
</metacity_session>

I've done this because of following line in the .xsession-errors:
Fenstermanager-Warnung:Gespeicherte Sitzungsdatei ~/.metacity/sessions/default0.ms konnte nicht gelesen werden: Failed to open file '~/.metacity/sessions/default0.ms': Datei oder Verzeichnis nicht gefunden

2. renamed the ~/.nautilus/metafiles/x-nautilus-desktop:%2F%2F%2F.xml so nautilus had to create a new one...
I had to rearrange some icons, but this doesn't care I guess :)

I haven't had the problem since 2 log-offs and 2 full reboots. Hope it works in future.