Minecraft Lockout HELP

Hey guys, I have a HP LP2475w computer with Windows 7 and I've come across this one problem a couple of times. Whenever I try to launch Minecraft it will work for about 4 minutes then my monitor always shuts off and says "Monitor going to sleep" or "Power button lockout". This always happens when I try to play Minecraft but all of my other games work just fine. Any suggestions or help?