Can someone pls help

Ok so I called dell again. And now they say its not a spyware but a memory issue. This is what happens sometimes when I power on my computer the dell logo screen comes on there is a black line that runs through the word dell at the top of the letters. On the outside of the blue word dell there are tiny white dots the computer will freeze and not go to the desktop. There are sometime where I power on I can get thru the screen mentioned above ok and then it takes me to a memory read/write failure screen which is black screen. I called tech support and they had me take out the memory and insert it back in. This weekend I was on the phone with dell for at least 4 hours. I am getting really frustrated because I dont know whats wrong. Another thing I got a message saying Activeshield is not properly installed. The tech had me take all mcaffee programs off. Now when I install using the cd they provided it gives me a message saying that all programs could not be installed like the mcaffee securtiy center....Oh and by the way I am at work and dont have the exact message on the blue screen. But its similar to this

" WIndows has been shut down to prevent further damage....."

Stop : oxoooooo50 thats the code I provided the tech....

Any input would be greatly appreciated. Thank you for your time.