Hi Martin, yeah to stabilize it you've got to try and narrow down what's the bad part.

For bad RAM the best way to test it is to use memtest86 http://www.memtest.org/ (you need to set up some kind of bootable method like set up a bootable USB key or CD-ROM), and let it run for a few hours or overnight and if it detects a failure, you can be pretty certain that it's bad RAM.

If you can get a failure on memtest86 then replacing the RAM would probably be your best bet. Or if you have multiple RAM slots filled you could try removing just one of them at a time and re-run memtest86 to see which one is the bad one.

- Michael