Voting keypads and bluescreens

One of the more interesting problems I was given at RAC is the issue of Turning Point voting keypads causing computers to blue screen.

For those who don’t know, the keypads allow things like voting by an audience using little keypads.  The signal is sent wirelessly to a USB receiver plugged into a computer.  Following the roll-out of RAC’s new Managed Operating Environment (MOE), plugging in one of the receivers would cause the computer to blue screen.  I was tasked with fixing it.

The initial route I followed was to examine the blue screen dump files using the Windows Debugging tools.  Doing so pointed to the drivers for the receiver being the cause and after googling a bit, there did seem to be some supporting evidence that these style of devices didn’t play well on Windows 7.

The change in troubleshooting approach came from the fact that, if the device was plugged into a freshly un-boxed HP machine which hadn’t been re-imaged yet (that is, it was running the manufacturer image and drivers), it would work.  There was a date difference between the drivers, with the ones in the MOE being slightly older.

Going on the theory that one of the older drivers in the MOE was causing the blue screens in some way, I downloaded the latest drivers from HP and applied them one at a time, testing the receiver each time.  Eventually I hit a point where the blue screens stopped and the culprit was the fingerprint scanner’s driver.

I reproduced the fix on a few other machines with success, so there must’ve been some incompatibility between the MOE’s finger print scanner driver and the keypad receiver.