striker, I have a long explanation but no time to type it all out. Do this, it should help
Download a program called bootvis
. It is a program that analysis your booting sequence which might have been cluttered with new hardware additions eg memory hdd etc. Go to tools then optimize. This will reboot the computer and analyse your booting sequence, then it will re-allocate the sequence for optimization. I went from 13 bars to 3 with this program so i know it works, and have used it on all the computers I have worked on at my internship (why i worked on comps i have no idea because it was an investment/finance internship).
Next please do a memory error test. memtest86 is one of the many out there, google will provide a zillion types of memory error testing software. this will isolate if you have bad memory or that your memory for some reason is conflicting with your original memory chip.
hope this helps and you get your problem solved