Green Lines all over my screen.

Hello there, I'm doubting if I should consult for this problem but I've decided to try.

Apparently, our probably a decade old Windows 7 Professional is having an issue regarding with the display, and I think graphics card are involved as well (not really sure).

Our screen is showing these green moving lines and it actually gets worse and it's not green anymore, a lighter color kind of those moving lines which hurts my eyes. These lines are also worst when it comes to black or dark colors, it's literally covered with those green moving lines.

There are times that it comes back to pretty normal but it only takes like seconds then goes back to moving lines. I'm pretty convinced that this is caused by its oldness. Our CPU (the shelf) gets beaten (literally) too before because our computer had this crashing then beeping issue. What do you guys think I should do with out computer? I'm not really sure when I'm going to have a new one since we're not that rich, I have lots of school related works to do yet this computer is already falling down? Or maybe we can still save it? Please give me some solutions regarding this issue.

As you can see on the 3 pictures I sent, they're just probably level 2 of green/light colored moving lines, it gets worse randomly.

It can be many things.
- Can be a bad contact. Try to take the monitor connector from the computer and monitor and put it back.
- Boot on safe mode. If the colors are OK, on device manager try to uninstall the graphics card driver and install it again.

Hello there, I tried safe mode and it's still the same, actually it acted up again and green lines showed up. Anyway, when I opened my PC I started to play this emulator (PPSPP) for a while since I wanted to test if it can last a while, it did but after probably an hour or two green lines showed up, then that's when I tried the safe mode.

I also didn't read the first step properly, I only disconnected the monitor connector from the monitor itself and not with the computer, got to work with it again, I'll post an update when I finished doing it.

About the graphics card thing, I'm not really sure which part of device manager I can find the graphics card driver. Is it under the Display adapters? I'm pretty afraid something will happen if I uninstall something important here. If it's under the display adapters, I have Intel(R) G33/G31 Express Chipset Family, is it the one I need to uninstall?

Plus, I saw some imaging devices that doesn't work, it says when I open it " The device cannot start (Code 10) ", two Lexmark X422 are having those warning signs. Not really sure if it's connected with the issue, I just wanted to point that out.

Quick update: I did the first step, even took a bit long to make sure it's screwed properly. Restarted the computer, monitor pretty much went back to normal again, haven't checked if it lasts tho.