William,
If you were able to program and debug in the past with this ARM10/ARM20 configuration, I don't think there is a problem here.
On my side I've generated a basic test code setting the PLL to 330Mhz with Halcogen,
I've programmed this code and I still can connect and disconnect to the target. Of course the code is not working correctly and I end up in exception. At any time I can still take control of the device with the debugger and erase the part.
I will really need the exact step and code that you programmed in the device to end up with this problem.
Without the same environment I'm not sure I can help a lot.
If you want, I can set up a webex and phone call for tomorrow morning.
just let me know.