I posted this problem under hardware because it's what I think might be the problem but I really have no idea!

I have an HP Pavilion dm4. It's about 1.5 years old, and for the last few months it will randomly freak out on me...the screen will turn into a green checkerboard pattern or sometimes it will go black.  It also makes a really loud buzzing noise whenever this happens.

This happens most frequently when I'm watching streaming video or playing League of Legends. It happens at other times too though.

When I have my laptop hooked up to a monitor w/ an HDMI cable, the monitor screen will also turn into the green checkerboard or go black depending on what my laptop did.

When this happens none of the buttons on my laptop work, including the power button, so I've resorted to removing the battery whenever this happens and turning my laptop back on. Everything is perfectly fine after this happens.

I have no idea what's wrong with it and I really need help! Sounds like the GPU ( Graphics Processor ) is overheating. I'd RUN a free utility called speedfan on this laptop and watch temps. The GPU might be roasting and then acting up.

If the GPU is not permanently damaged and is overheating according to SpeedFan, you can fix this by making sure the GPU heatsink is free of lint/dust, as well as verify that there is adequate airflow. I would even go to the extreme of removing the GPU heatsink carefully and verifying that it has adequate thermal compound applied to bond the thermal heatsink properties of the heatsink with the GPU chip face.

If the GPU is not getting too HOT and it is acting up it can be a bad RAM stick possibly SINCE memory is shared between the CPU and GPU. A test for memory is Memtest86 which can be burned to a CD,DVD, or you can make a bootable USB flash drive to boot this from and test at least 3 full TESTS. Anything in RED text is indication of memory issues. So if this is the case, replacing a bad ram stick could fix it.

I am thinking its a GPU that is overheating.