Windows NT will normally lock up if you attempt to boot it from a FAT partition that starts more than 2GB into the disk. Using BootIt BM, you'll be able to boot NT from above 2GB on most systems. There are some system BIOS/Disk configurations which will still prevent NT from being booted above 2GB. Under those systems, you'll receive an "NTDETECT failed" error message.
Additionally, if you're attempting to boot Windows NT from a partition above 8GB on the disk, you may receive only a flashing cursor in the upper-left corner of the screen.
For addtional information see: