I bought two sticks of 256 Rosewill RAM for my Dell 4100. I put both sticks in and my PC would not start. My PC works fine with 1 stick in the first slot, it doesn't matter which stick. My PC doen't work at all with either stick in the second slot. So that leads me to believe the problem lies with the second slot, but my old RAM does work in the second slot (2 sticks of 128). Any suggestions?