Arduino board reset after 30 seconds

When Arduino board is connected and powered by USB cable from computer with windows my board is resetted every 30 seconds. when powered from cellphone charger it works ok.

What is the question ?

There is a good chance that your computer does not provide enough voltage from its USB port.
This is especially true for cheaper powered hubs too or computers where a lot of USB items are depending on power from the ports.

Phones do need a set voltage to charge so probably why it works from there.

Maybe give it its own PSU.