My Quantum Programmer suddenly stopped communicating with the test track I use for programming.

The first indication was not being able to read a decoder using the Q upgrade, same result using the CV manager. I get either 'cannot read mfg.' or a RS232 error.

I've verified the 'track' was enabled and the programmer receives power. I am confused as to which is the correct SiLab driver for my WinXP system: the virtual port or USB, even though it is connected through a USB port. I have been unable to verify whether the driver installed has changed.

I got to the point where I upgraded both the CVM and Q Upgrade to the latest available versions. I also uninstalled the programmer and drivers, and re-installed everything.

The programmer worked fine one day, then not the next. Tried on both an aftermarket QSI decoder and a OEM Q3 decoder.

I have seen comments about a resistor blowing in the programmer. Is there a way to test the hardware?