Calculate Time Duration Spanning Different Days

This is driving me insane:

I'm trying to calculate the time difference between two cells. The problem occurs when the time spans multiple days. For example....

Start date: 11/2/2009
Start time: 9:06:04 PM 1
Stop date: 11/3/2009
Stop time: 3:22:19 AM

I would like the output to be in hh:mm:ss format.

Any suggestions would be appreciated.

Mike