I could not find anything in the forum and I am running out of ideas.

On Ubuntu 11.10 a specific user has this problem: he is presented with the shut down dialogue after 2 minutes of the session starting or right after firefox starts up for the first time in the session. This is consistent in both Unity and Gnome and with any kernel version. The dialogue does not appear to any other user. acpi has been checked (started with acpi=off) and it does not seem to be a problem. All addons disabled in firefox. .xsession-errors does not show anything when the dialogue appears.

I think an event happens 2 min after the session has started and the same event when firefox starts up for the first time in the session which causes the shutdown dialogue to appear, but what could it be? Any ideas?