"Searcher7" wrote
-However I have no idea why it would make a difference, because as I
-mentioned there would be no current during "make" or "break" of the
-connections.
-Darren Harris

Even after we told you the reason.

BTW, if the ground connection fails or is made after the others, the
+3.3 supply line (for example) could disastrously become the return
for the +12V.

http://en.wikipedia.org/wiki/Hot_swapping