Automatic Shut Off

I bought a pre built PC from Best buy. Price was very reasonable and building it would've cost more. Anyways, recently I've noticed that my PC reboots when I try to use it. So let's say I used it on Monday and I leave it on. I come back in either Tuesday or Wednesday and as soon as I open Chrome or any other program it will automatically restarting saying "We ran into a problem". Is there anything I am doing wrong? Is there a setting that needs to be adjusted?