[CentOS] Gnome Screensaver - not functioning as advertised

Hi List,
Currently running a couple of CentOS 6.3 workstations / laptops with 
gnome as the default window manager.
Since the original 6.1 install the behaviour of the screensaver has changed.

I use the cosmos theme and have this activate after five minutes of idle.
Initially, when the five minutes were up, the screen would start to dim 
and if one moved the mouse or hit a key on the keyboard it would drop 
out of screensave and return to full bright screen.
With one of the updates since then, the behaviour has changed - now once 
the 5 minutes are up - one has to wait until the gradual dimming of the 
screen is complete (a couple of seconds) and only then move the mouse or 
hit a key to show the password dialog - enter password and then get a 
working screen - all quite time consuming.

So I thought, remove the "Lock screen when screensaver is active" - I 
have unchecked this option, logged in and out, and it just ignores it 
and insists on a password - always.

I guess there is some option buried deep within the gnome system panel 
that needs some attention - any ideas?

My preference is to have it back to the original behaviour, once the 
screen begins to fade, a mouse movement or key click prevents the 
screensaver from gaining complete control and needing the password entry 
dialog etc. all my precious seconds being wasted - especially as I have 
a 5 minute idle setting.

Suggestions welcome
TIA
Rob