I just stumbled on something strange. I was using a tool called "MbrFix" that is capable of writing DOS/Win9x bootsectors to a partition. I was using it to create a FAT32 bootsector to load Win98's DOS rather than NTLDR. At any rate the write wouldn't stick. The write would "take", that is, I could see the changes via a sector editor, but a few seconds later, it reverted back to the previous boot sector. It appears there is some protection code running that is monitoring the boot sectors for various drives and undoes any changes made, sort of like system file protection. XP 32-bit does this, as well as XP x64. Now, the "bootsect" tool from the Win7 distribution will work fine, changing back and forth between BOOTMGR and NTLDR calling boot sectors. It must know some "special API" to get around the protection. I had no idea that any such protection was in XP. Can anyone here confirm this, and is there a way to turn it off? Thanks.