Just based on the description above I would look at the cable. Make sure there are no breaks, there are no hubs between the iPod and the computer.
Next I would look at drivers: Updating the drivers on your Windows PC
Other concerns would be bad install, so an uninstall and reinstall may be needed: Trouble installing iTunes or QuickTime for Windows
Apple does have an article covering all the possibilities: iTunes for Windows Vista or Windows 7: Troubleshooting unexpected quits, freezes, or launch issues