Hi.
If the camera USB connection was working before and the problem suddenly happened on two different computers, then it is not a matter of driver.
Try removing the camera batteries. Remove both main battery and coin shaped battery. Allow the camera to rest five minutes with no battery.The power drain may resolve issues caused by accumulation of electrostatic charges.
While camera is OFF turn off the desktop, disconnect power cord, connect back and restart. (I don't think the computer is responsible...just in case do PC power drain and restart to do the same on laptop also remove battery).
Connect back the camera using a DIFFERENT USB cable.
If that still does not work, then one of the contact in the camera USB socket may be faulty. Check if there is a bent pin. If there is nothing visible, then one of the solder joints at the back of the camera may have lost connection. In that case the camera must be disassembled and repaired. If you need to send the camera for repair see the number listed on the owners manual or get a quote online here (working days):
Repair. An alternative to repair could be using an external card reader.
Do first the troubleshooting suggested at start of my comment.
Regards.
Ginko