Always worth checking on a non-windows 7 PC (so you know whether or not the controller is just broked, or if it's a windows 7 problem).
The usual tips are
Disable the UAC.
Log in and/or Run as admin.
Turn off the virus scanner.
Install the latest .net framework 4.0 or newer.
Try the USB ports on the back/front/side of your computer.
Use fresshhhhh batteries (low battery does not have enough power the USB, low batt can be 2.2-2.3V, USB requires more than that) Your mod might work fine but the USB won't, this is from batt's.
Don't pirate Windows 7 (not your problem in this case)
Be sure to run Windows Update and take all those Microsoft patches... they fix lots of weird issues...
Uninstall any other USB device software, especially software related to CELL PHONES! (no shit this has been an issue for several users)
Take the latest bios/firmware upgrade available for your motherboard
Again I would try on a different PC first to make sure the controller is actually working, if it is working, well then you've got your hands full of things to try.