[Resolved]  Microtek Sinewave 1400 — computer reboots

I have purchased a Microtek Sine Wave Inverter a year back.
It is giving me trouble within a couple of months .My computer reboots (restarts) when lights go off instead of picking up on inverter.
I complained to the dealer from whom I had taken .He only helped me by replacing the batteries.But my problem remains the same .He is not able to understand find a solution to it.

Kindly provide a service personnel who can advise me what should I do in this situation.

Thanks.