Arduino not recognized

I create CNC panel using :
2 power supply 24v 12A
Arduino uno (5v from USB)
3 pcs Tb6600 driver.

I screw arduino to metal panel box.

When Power supply off, connect arduino to PC using USB is detected and normal.
But when powersupply ON, suddenly win7 could not recognize arduino.
So i release arduino from panel box (unscrew) and powerup the Powersupply, win 7 can detect arduino successfully.

So what is the problem? Why everytime powersupply is ON, arduino not recognize by win7.

Without seeing a wiring diagram it's difficult to know what might be the cause.

...R

This is wire diagram

So i release arduino from panel box (unscrew) and powerup the Powersupply, win 7 can detect arduino successfully.

It seems self evident that the problem is how the board is installed in the panel box. Something is touching something causing a bad connection (short?).

Image from Reply #2 so we don't have to download it. See this Simple Image Guide

...R