My first question is have you tried a different USB port? Sometimes it could be a USB port issue and another port could work.
Please check and try another cable if possible if not or another port doesnt work please try the steps below
FIrst thing we need to do is download the windows installer clean up utility
You can download the utility here it is a utility in windows that can remove programs as long as the windows installer has access to them. Save the file to the desktop, right click on it and say run as administrator.
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 Bonjour, Quick Time, Mobile Device, Itunes
Once this has successfully removed
do a reboot/restart your computer.
When the computer comes back up go download a fresh install from apples website
The go to C \Program Files\ and delete the itunes folder
The go to C:\documents and settings\YOURUSERNAME\Application Data\and delete the apple computer folder and one that says apple if there
the go to C:\Program Files\Common Files and delete the apple folder
Reboot after reboot run the install for itunes you downloaded earlier
Please let me know if you have any questions
Edited by Omer Mushahwar on 8/3/2010 at 8:11 PM EST