Can't update Ipad to IOS 4.3.2

[TSH]

When I try to update IOS I get the following error message: iTunes could not back up the iPad because a session could not be started with the iPad. I have updated all software and Itunes, changed USB cables, repaired permissions and restarted computer. I still get the same error message. All of the sync functions work but when it comes to back up it just stalls. This has not happened before. Any suggestions?

 

[twerppoet]

Have you tried restarting the iPad?

Hold down the power button until the red power off slider appears, and slide it off. When the ipad finishes shutting down, hold down the power button again until you see the Apple logo.