BOB\Driver crashing? on CNC Plasma table.

[gr8fun]

Hi Everyone.
I've had my plasma CNC table working for a few months, however today it has stopped playing ball.

I have a driver which is the PM542 model.
The BOB is the ZP5A-INT Breakout board from Zapp Automation

I can boot the system fine and manually home the 3 axis, I then start the code running and notice when the plasma pierces there is a lot of interference on the CRT tube screen I'm currently using. Once the pierce has finished the screen is fine.
However during a pierce, one axis will stop.
The screen shows everything all fine and dandy, but the cut is a straight line.

If I disconnect power to the power supply and therefore the drivers\BOB it seems to "reset" and be fine.... until another pierce, not all pierces, but enough to ruin the job.

I suspect there is some sort if interference when the pierce takes place, the BOB\drivers are mounted to a board that is above the PC, but below the table and directly next to the plasma cutter.

Does this sound plausible?
Should move\shield the drivers\BOB from the plasma cutter\PC ?

Any ideas how to stop this from happening?

All advice greatly received.

---More info---

I have plugged the plasma cutter into a scocket on a differnt wiring ring to the PC and things *seem* to be better. I'm loosing a few steps now instead of the whole thing crashing, which is certainly better but still not perfect.
The losses definately happen when the arc is being struck.
Any ideas?

Dan