Computer Restarts when Hardware is connected

Registration date
Monday November 30, 2015
Last seen
November 30, 2015
Dear Sir,

Kindly help me in the following issue:

My computer continuously restarts whenever i connect any external hard drive/pen drive. Due to this, I used to switch off-in my power button due to which my internal hard drive got crashed. I recently bought a new hard drive and my engineer has installed a OS but the same is still occurring. My computer works good for some time if I don't insert a hardware.

I want to know whether its my OS issue or SMPS Problem. My engineer keeps charging me for the same problem again and again. Kindly help !!