Computer hangs

My computer is hanging, online or off it hangs. The monitor starts blinking and the colors are all mixed up in blocks. The cursor moves but does nothing and it looks like an oriental letter

I thought it might be heat so cleaned everything real well. Didn’t help. Thinking it might be my ram I downloaded a memory scanner and ende up with tidynetworks, sweetpack and wajam. Ran Spybot S&D and deleted the above entries, that I found, from the registry.

Need advise and directions. Am using a common computer in my apartment building to ask for help.

Thanks, Brett