I am using Ubuntu 11.04 , on a DELL Vostro 1510. If I am inactive for a certain time, the screen usually gets locked and the login prompt will be there.

Yes sometimes I am able to see the login screen and logging in as normal. But sometimes after its locked and when the mouse or keyboard is moved also nothing happens. This is happening for the second time. And its not happening always .

I can switch from one terminal to other from the locked screen with Alt + + Ctrl F1 etc . But when I switch to the graphical one with Alt + Ctrl + F7 ( from the locked time ) I can see only a blank screen.

I tried once login in ( Alt + Ctrl + F1 ) and trying to startx, but it said something was locked and want to delete the lock and try. So I removed don't remember what exactly it was . But it too was not a success , I was forced to press the powerbutton.

Is this a bug ? I saw some but all are happening for switching users. Never experienced after logging out, but this happens only when its locked automatically actually.

Update :

I strongly feel this is a Bug. As I upgraded to 11.10 , I didn't noticed the same issues. But at some point if any one has an answer, you can post it. I can approve.