OK, I noticed this problem about a week ago when I was playing a PC game. Just all of a sudden, my PC completely turned off (mouse light, keyboard lights, and power light were still on). The only way I could turn it back on was by holding the power button for a good 5 seconds and turning it on. At first I thought it was the game causing these problems but it happened a few more times while I was randomly doing things on the internet. Whenever I turn the PC back on, I don't get any type of error message so I have no idea what's the problem. It would be a big help if anyone knows a soultion to this problem. Thanks.

Your power supply unit may be starting to go.

The fact that you had to press the power for 5 seconds and then it worked makes me think that your system went into standby. That might be caused either by the state of the battery(if this is a laptop) or by software settings.

You can go in Control Panel in Power Options/ and set everything always on there and see if the problem reoccurs.

Well there was actually one time where 30 seconds after i turned my PC back on, it completely shut off again! So, now I uninstalled the previous game I had because that seemed to be the cause of the problem because I didn't have these problems until I got the game. Now my PC seems stable right now but I'm thinking of getting a new one.

ok, the PC is acting up again and I juss want to know if anyone knows how im able to prevent this from happening again. thanks

I'm going to go with what I said before: Power Supply Unit... I'm not really 100% why it woudl happen after your game was installed, but I'm thinking it is your PSU