Laptop has black screen on startup until I restart it

Hello,
I got a used HP15 laptop a few months ago after my parents had had it. When I got it it was kind of slow, but it's definitely gotten slower since.

Only recently though when I close it without turning it off and come back to it even just minutes later if I open it the screen is black. This has happened every time I've opened it for a few days, the only thing that works is restarting it.

Is this the result of a virus or is there something wrong with my hard drive or motherboard?

Also, if anyone else has a problem in Windows 8 with any Internet Browser just eating up way too much RAM, that's been an issue as well with both Chrome and Firefox.