Do these

You don't need to re-install the system. your pc u***** root hub driver were corrupted because you did not follow the rule: unplug u***** device by stopping it first, except for printer and mouse!!! You can now do these:

1. use "Device Manager" to verify, by right clicking "My Computer" - Properties - Hardwares - Device Manager", where you can see the u***** controller icons with yellow "?" marks

2. uninstall bad controller drivers

3. use Dell "Drivers and Utilities" CD to re-install the drivers.

note: insert cd and it will run automatically. if not, open cd and click autocd executable file, it might prompt you to install setup files, just click OK, and follow the instruction on the screen.