I have installed WinXP on separate hard drives. I am manually plugging in only one of the 2 drives at a time so there is only one physical boot drive (C installed. (I should note that each drive has its own SATA connection to the mobo, since I plan on using DD to hide one of the drives and select a boot drive from the mobo boot sequence, thus avoiding having to physically plug/unplug drives.) I also have another drive (D in the system for data. I am getting the NTLDR boot error when I connect either one of the two boot drives with D: connected. However, if I disconnect the D: drive, either C: boots just fine. Then if I power down and reconnect D: after C: has successfully booted by itself, all is well. But when I switch to the other boot C: drive, same problem happens and I have to go through the steps to make it all work. (If I select the boot drive manually during the motherboard boot sequence, I can get things to work...but I have to do this on every boot.) When both C: & D: are connected and I boot from the DD CD, it is showing my data drive as C: and C: as D:, which is wrong and probably the source of the NTLDR boot error problem. D: is not a boot drive, no OS installed. But it is partitioned as Primary, Active. Could this be the reason why I am getting this drive letter confusion? Could the fix be to remove the partition and reformat as Logical?