My long-suffering Geiger counter is now back up and running.
Now, as has been pointed out, this particular instance of this experiment is really an experiment, and is run only by me, for only experimental purposes. It doesn't represent any opinion or endorsement or opinion of any entity, whether the University of Chicago Library or the University or anything else. It is not a service. It represents nothing, is not calibrated, and should not be relied upon by anyone for anything. Don't email or call anyone but myself about it.
This instance is located in my office on the A-level of the Regenstein Library, the first basement level of a six-story building. The levels average about 8 microrads/hr here. Outside at Ryerson Physical Laboratory on the fifth floor, levels average to about 12 microrads/hr, which indicate the shielding provided by the Regenstein against the cosmic ray flux.
The problem I've been having with this counter was with the associated AW-SRAD software, which runs under DOS, doesn't appear to support virtual COM ports above COM4. On my Windows XP PC I had installed an Arduino which offered a similar USB Serial converter and I theorize at some point there was a conflict and the Geiger counter with its FTDI USB to serial converter took a high COM port at COM5. After removing the Arduino, I then disabled the real serial port at COM1 and forced via Device Manager->Ports->USB Serial Ports the port to go to COM1.