What's with Gnome not logging out?

[AG <computing.account@googlemail.com>]

Hey all

On an up-to-date testing machine using Gnome 2.30.0 I often experience 
difficulty logging out of a desktop session.  To date, I have to either 
reboot the machine or stop and restart the gdm, neither of which is 
ideal and seems akin to cracking apeanut with a sledgehammer.  The 
option to log out of the session under the panel menu/ system doesn't 
work nor does the old three-finger salute of ctrl+alt+backspace.

Am I the only Gnome user experiencing this and if not, has anyone got a 
suggestion for a decent work around?  Searches on Google show a few old 
threads but nothing current, suggesting that it may have been a 
temporary glitch.  The Gnome user list is either dead or sparsely 
populated as there is very infrequent activity there and my query around 
this has not been addressed for several weeks now.

Thanks for help.

AG