I have been having problems with the USB ports on the desktop for a while now, knew the USB ports at the front were broken, so tried to utilise a couple of spare on the back.
all to no avail. Last week I had to buy a new printer (bit of a bummer really, I have one in the shed and thought my old one would see me through the next few weeks) however when I plugged the printer into one of the back USB ports, it would freeze the mouse, disconnect the modem for the broadband and I would have to reboot the computer and disconnect the printer.
I had some time this morning and took it up to the computer shop for them to look at. They disconnected the front USB ports from the motherboard (I think that is what they told me) and now the back ones work fine again. Apparently it was to do with the bits inside the USB ports touching parts they shouldn't, and thus created a 'short' (my words).
I have bought a USB extension cable and a 4 port hub to plug in any future devices without having to pull out the desktop from its home in the office cabinet. A cheap solution all up $17.
They said it was possible to replace the front ports, however would have to find something that fitted in the existing cabinet. I am happy with the solution I have though....