Just to be clearer is this a usb hub or are you connecting directly to the computer? If a hub what happens if you connect the e7 directly to the computer? If you connect directly to the computer does the phone connect in Nokia suite or appear under My Computer? What happens if you connect another usb device using the same port?
I hope you find a solution.
I wouldn't think removing Nokia suite & all the other Nokia components then reinstalling would fix the problem which is a shame as that usually fixes many phone/computer connection problems.
I don't think it's to do with Belle - I am still on Anna and I have the same issue. I think it is a hardware issue with the USB charging port on the E7. It also affects my charging - my Nokia charger never works anymore - I just get a USB error on the phone. My wife's Blackberry charger works, but only if I quickly wrap the cable round the phone so the USB plug is pulled away from the front (screenside) of the phone. You have to do this quickly, before the light comes on. By this method I can even connect to the USB port on the computer, but it's a bit hit and miss. I have read elsewhere that the USB port is dodgy on many E7's.