Trying to install the NEC ND-3520A from Newegg into my dimension 4500. The unit came OEM-no documentation. When I removed the Samsung burner and installed the NEC DVD burner all the other drives are unrecognized. In addition to the Samsung burner I have a Liteon DVD ROM installed in the top bay with a Iomega zip 100. Those drives are the lost ones referred to when I installed the NEC. As soon as I replaced the Samsung back in all was well again. The NEC does not even have a "driver or firmware update". I sure have been striking out. Any thoughts or experiences. Thanks.