When you say corrupting, how so, what file is failing or is it just reluctant to boot ? When i have done dual booters in the past i have created two partitions initially both FAT32, then once NT is installed on the required partition it is simply a case of using the convert command. At least this way you could boot to a DOS prompt and see exactly what is going on with the NT partition and even manually edit the BOOT.INI if need be. Hope this helps