heard 3 beeps, then removed 1 memory stick and it works

when memory card is in the first slot, i hear 3 beeps at startup, but then when i start up with only one memory card in back slot, it starts up, but the mouse is jumping all over the place and i hear "machine gun fire" through the speaker of my separate monitor. It does settle down after i use it but now i see that there is a larger problem in that the outer memory slot fails to allow a startup when a memory card is installed in it. I switched the memory card and it does not make a difference. Any help would be very much appreciated.