This happened to me a while back, too. Strangely enough, right after I had updated Windows.
I didn't really fix it at all... intead I just ended up completely reinstalling windows, which made the problem go away altogether.
Now, after some googling once I saw your topic, I found this:
The solution is to make sure you stop the usb device prior to unplug, not just ejecting from itunes but stopping the usb itself.
How to fix:
Turn off computer.
Plug ipod into usb.
Then you must reset your ipod... don't worry it won't wipe anything out.
To reset move the hold button ( on top of the ipod) once to hold then back to original position.
Then press and hold the center button and the top menu button at the same time for 6 seconds.
Start computer and it should install the usb driver for the ipod automatically.
Your I pod will say do not unplug so don't. then open itunes and it will be there.
Just remember to not only eject ipod from itunes but stop usb.
Go to the program icons near the clock and right click the usb icon and "safely remove hardware" will appear and click it.
Stop it and select "apple ipod".
I'm not sure if this worked for the person who had orginally requested help, but there were no posts after the suggestion, leaving me to assume that it did.
Give it a try?
This is a answer I found . I think it help you !!!!!