[Thinkpad] T40p logs off user when suspend or hibernate

[Laurence Spiegel]

Hi - 

I have a sudden, baffling problem on my T40p which has had no previous issues.  When resuming from sleep I find it has logged the session off and lost all work. 
detail: If I enter sleep mode, either via timer or closing the case, I will be presented with the normal pick-a-user screen on wake (I have fast user switching enabled). After entering the password for the session I was just in, it does not bring me back to my previous workspace - it logs the user in, losing all state/work.  
Strangely, hibernate works perfectly.  I have made no changes to either software or hardware between the time this worked reliably (yesterday) and when the function broke (today).

How do I troubleshoot this issue? 

thanks in advance