About a month ago I purchased two 2GB kits of RAM. Each kit came with two 1GB (PC4200 DDR2 533 PC2-4200) low density chips. Once I recieved the two 2GB kits, I installed them into my computer. After installing the RAM, I turned on my PC and my OS began to start up. Once Windows Vista started up, I went to Control Panel then to System to make sure I had the right amount of memory (4GB in total); I checked and noticed that only 3GB was showing. At first, I didn't understand why there was only 3GB rather than 4GB. So, I shutdown my computer and took out all of the chips then put them back in. I turned on my computer and checked once more but there was still only 3GB showing. I was confused. I tried once more. I shutdown my computer, took out all of the chips but this time when trying to install the RAM, I struggled a bit. I managed to get them in; however, when I turned on my computer, instead of getting the Dell boot screen as I usually do before Windows starts up, I got a black screen with white letters and numbers on the top left corner. I can't remember exactly what it said but I remember seeing DDR2 some where inbetween. Everytime I try pressing Enter or any other key on my keyboard nothing happens. I turned off the computer and powered it back on but got the same message. I turned off my computer again then took out the RAM once more to check if there were any visible scratches or cracks on any of the chips; but nothing. This time, instead of putting all of the chips back into the computer I decided to put just one set (2GB) of RAM. After putting the 2GB of RAM I turned on the computer and got the same black screen. At that point, I was convinced that the RAM was damaged due to my struggling when trying to install it. I took out the first set of RAM then tried the second. This time the computer booted up and Windows Vista began to start. I went to Control Panel then to System to see how much RAM was showing up; it showed 2GB. I said to myself, "Okay, then I must of just damaged the other set of chips." I accepted the fact that the other set of RAM was damaged. A few minutes later, suddenly, the screen goes black then "The Blue Screen of Death", as they call it, pops up and my computer reboots. It does this every time I have the memory sticks installed into my computer. I'm left with no choice but to use the original RAM that came with my PC. Why is this? Is my second set of RAM damaged as well? Or is there something that i have to do? Any suggestions would be greatly appreciated. Thanks in advance.