I use the BDM from Witztronics.com, but the P&E BDM should work the same.
You need to enable "trace" (under the BDM menu in the debugger).
Then set some Trigger points. You have multiple options and combinations with two triggers, trigger A and B. You can trigger on address read/writes, memory read/writes (Ports are just memory locations), ect... You can even set up complex triggers; ie. If trigger A then trigger B...
Find a combination of triggers that will stop the processor when it starts throwing out signals and you can look over the trace buffer to see what it was doing before this happens.
You may have to learn how to use the triggers first, but it will be well worth it in the end. This is what debuggers are for.
uCTechnoGeek