It may be that, since you've moved up to iOS 5.1.1, that this tutorial outlined in this thread will no longer work. IOS 5 changed a lot of things and so you can no longer downgrade to 4.3.3 using this tutorial.
However, there is hope! A new tool was just released by redsn0w to downgrade off of iOS 5.1.1 and my honorable and esteemed colleague, f4780y, has made a tutorial on how to use it. See it here: http://www.ipadforums.net/showthread.php?t=76087
So, give that process a try and see if that helps you out. Good luck and do let us know how it goes.