I would try getting the latest firmware for the small business switch.  This could easily be a firmware issue.  I think this is the most likely issue.  Perhaps the switch is crashing rather than powering down.
 
My next guess, which I think is unlikely, is some kind of PoE mis-negotiation is happening, and both ends are trying to apply power (and causing a short, or something like that).  Perhaps see if you can disable PoE on the port on both ends.
 
I'm assuming you have tried a different patch lead already?