iphone4 will not backup or update OS

[jerry.peoples]

i have a user in my company whos iphone basically either freezes when he does a general backup or it freezes when he tries to install the new OS.

i have tried the following:

ensure he has admin rights
uninstalled itunes
used ccleaner to remove registry remnants
reinstalled itunes
plugged phone back into usb

it still keeps his information completely, all apps, songs contacts.

if i deleted itunes from the PC and then reinstall, shouldnt it ask me for his itunes credentials or will it pull those of the iphone automatically?

i am at a loss as to how to help him out with this. i believe it is somehow data related but am not sure how to go about deleting the problem data if that is indeed the problem.

any help would be greatly appreciated.

thanks,

Jerry