Could this be due to my power supply? My screen randomly turns blue(I just reformatted, and it still does it), and then pc shuts down, and I need to turn it off and then restart it before it turns on by itself.

I'm thinking it's due to my power supply perhaps? Is there a temporary fix I may do, maybe with the BIOS settings or something? I can turn off my DVD player(well dvddisc or whatever it's called), but I don't know how, maybe that will help?

Most likely a video graphics card, or the video graphics driver. The fact that it shuts down tells you it could also be memory, or the hard drive...
Yes it could be the power supply, since the problem appears random. A good power supply tester is $12 to $24, but if you have access to another power supply, that will be enough to test the system.
You might want to create a bunch of tests, starting with a power supply, floppy disk with MSDos or Windows 98, and one memory module connected to the video card.
Then boot in SAFE MODE.