I have a Dell Optiplex GX270 that I installed a new Seagate Barracuda model 7500.10 part no. 9DJ04E-305 250 Gb hard drive in. The O/S, Windows xp, installed but the hard drive is not recognized in the BIOS unless I install the jumper in the master position, when this is done the computer boots to the black screen that says "NTLDR missing". I have installed the NTLDR file in the folder I found it in on my laptop but still get the same results. This is the only hard-drive and I flashed the BIOS. Any help would be appreciated.