blown Gecko - shorted output ?

Hi all,

I blew us a couple Gecko 201's over the last week. Yeah, I'm
thinking of pre-purchasing some of the more bullet proof ones when
available.

Here is my situation.

All steel frame, steel on steel everywhere so there are not sections
that are electrically isolated. No fur-lined linear slides.
Steppers mounted on aluminum so are also electrically common to the
frame.

spindle power is 110VAC and grounded to the frame.

Power supply is an old PC box and is grounded to the 110VAC. same
wall outlet as the PC.

PC is powered 110VAC, and I did have it in another wall outlet,
didn't check if it was on the same phase or a different phase.

infinite resistance between my power supply and the frame.

I triple checked my wring for possible shorts, bent and twisted
everything to see what I could find. everything looks good, infinite
resistance on each lead to lead and leads to ground.

Infinite resistance from all the wires to the frame and to the power
supply.

I bench tested a stepper, worked great. mounted it on the machine
and pop. blew something in the Gecko. Mariss said it might be the
outputs but only testing will reveal the answers.

so my question is of isolation. does the Gecko frame need to be
isolated from the power supply ? from the 110VAC earth ground ?

what irks me is that one axis has been solid for the duration, runs
perfectly. the other had 'eaten' 4 Gecko's. as you can imagine I'm
not excited to just throw on another Gecko to see what happens.
What bothers me is that I ran all weekend with no problems. 2 I blew
on setting up. I assumed that I did something stupid, but now that I
blew up another 2 with everything I knew to test, tested, I am
nervious.

HELP !!!

Dave