typically when I see a hung PID on my boxes, I can tell that it is hung usually because the run time is very high (somewhat subjective) and the CPU usage is usually very high as well.
We call those "runaway processes". At my work, we use BMC Patrol as a monitoring tool. If the process runs for longer than X minutes, it is flagged and I get a page or email depending on how I have it set to notify me. Also, on HPUX, I have the "top" command and "glance" that help me diagnose system usage.
You can ps -fu user, if you know the user who started the Process and capture the PID if the time and cpu useage is high.