I have a stock acer AM1100-b1410A that I updated to windows 7 64 bit home premium a few weeks ago. I still had the original 2GB of RAM installed. I then ordered 2 more 1GB sticks at the 533Mhz speed and recommended by the retailer for my computer. When I installed the additional RAM, the unit boots up and when music is supposed to play, it just crackles on the speakers and my network cannot be found. I installed the new ram by itself in the first 2 slots and it works fine. I install a module in the 3rd slot along with the first and second and the unit is fine. Same with the 4th slot. So, the unit works with 3GB but not 4GB. When I go into computer properties, it shows that I have 4GB. I am wondering if anybody can tell me why my sound and network ports and getting messed up? I try to look up an updated bios for this model through Acer and it shows none available. Any help would be much appreciated.