Hi I am one of the other experts here on just answer.com
I see you are running Vista there are a few things we can try.
First please click here on this page is a link to a utility in windows that can remove programs as long as the windows installer has access to them.
Once you install this
Click Start > Click All Programs > Click on the program Windows Installer Cleaner Utility
You should the be given a list of programs this can remove please check all Apple programs that appear ie Quick Time, Mobile Device, Itunes
Once this has successfully removed
Go into Internet Explorer Go to Tools go to internet options Click Reset in the window that comes up hit reset again to reset your settings this should clear up the AppHang error.
Now once this is done do a reboot/restart your computer.
When the computer comes back up click start/windows icon on taskbar
then in the command prompt type in : SFC /SCANNOW
there is a space after the SFC hit enter let it run through the verification process this can take some time
This Scan should check for errors in the windows file system.
After this scan is done and it fixes errors do another restart.
When the computer comes back up go download a fresh install from apples website and run the install
Please let me know if you have any questions