external drive install causes error for other partition
First off, hi all. I'm a new linux user, and am looking forward to figuring this stuff out. So here's my problem: I am attempting to install backtrack 4 to an external drive, partitioned as follows: ntfs (storing movies, etc), ext3 (linux partition), and a swap partition. Everything seems to work fine at first; I am able to boot into backtrack from the external, and boot into vista from my internal drive. However, any time I try to install linux, it screws up my ntfs partition on the external. Vista claims it isn't formatted; partition table doctor says theirs an error in the bootsector. I am always able to correct the error without data loss using fixboot from partition table doctor. After doing this however, grub fails to load when trying to boot off my external. I think it has something to do with the first partition on my drive being marked as bootable during the backtrack install process (or something along those lines). Anyways, what should I do to be able to both access my ntfs partition from vista, while also being able to boot linux off of my external. I'd rather not reformat my external if that can be avoided.
Looking forward to a reply.