Hi found the solution to the pesky lock symbol on the net, thought I share it with you so the solution spreads : Press and hold the two bottom buttons (4+5) for 15 seconds. the lock symbol will "unlock" after exactly 15 seconds and you are now able to use the OSD menu again! Funky part is that this is not mentioned in the Dell U2711 manuals (haven't been able to find anything about it). JG  
Hi, My U2711 monitor OSD menu had locked out itself. Self had tried as per instructions to hold button (4) for 15 seconds to unlock but that didnt work. The "LOCKED" symbol still stayed on the screen. Self had tried the self-test; button (1) + (4) and the test works, hence button (4) is working too. How do I do a hard reset to clear the firmware or reset the menu to original state and unlock? Thanks in advance for any advice. cheers..
U2711, OSD locked?