the / filesystem, to the best of my knowledge, cannot be reiserfs. You must have an ext2 or ext3 filesystem for /. After that, if you have other partitions declared, they can be reiserfs.
The reason is, in order to read a reiserfs filesystem, the OS has to load the reiserfs module. If the module is stored in a reiserfs filesystem, along with everything else, the OS will not boot.