when you installing linux distro with windows system(windows first installed).linux setup will ask you to put boot loader record on your MBR (Master Boot Record) or first sector of boot partition(that mean your VBR-volume boot record).you can decide which is suitable to put your boot loader record on.
Most people don't know what's the different between MBR and first sector of boot partition.
if you selected the place where is suitable to put your boot loader record. then Linux will modify your existing MBR or first sector of boot partition(VBR) for attaching GRUB or LILO boot loader with your existing NTRLD windows boot loader.then Linux will create a new boot loader record for booting process.
The GRUB or LILO(select Os) screen no longer appears and the PC boots straight into windows. The linux partitions appear in XP disk manager as
"unknown. Use Disk manager to reformat the linux partitions as NTFS and assign a drive letter.
But above solution is not safe and it's can't be expected as always working.since if you selected first sector of boot partition(VBR) for placing boot loader record then "FIXMBR" is not deal with VBR, that is the reason.
Before using BootIt NG on any system for the first time, back up all data on all hard drives. It’s better to be safe than sorry.