grub bug reading partitions?

[P]

Hi, I can't seem to get grub 0.93 to read
some of my partitions (that can be mounted
by linux fine whether normally from a disk,
or loopback from a file). Note the grub shell
within linux and the native grub show the
same problem.

It used to work when I had just 2 primary
partitions, but I think that was just by chance?
The working case is shown below.

======== Good ================================

grub> device (hd0) /dev/loop2
grub> geometry (hd0) 1000 2 32
drive 0x80: C/H/S = 1000/2/32, The number of sectors = 64000, /dev/loop2
   Partition num: 0,  Filesystem type is ext2fs, partition type 0x83
   Partition num: 1,  Filesystem type is ext2fs, partition type 0x83

--- corresponding fdisk output ---------------

2 heads, 32 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes

        Device Boot    Start       End    Blocks   Id  System
         part1            32      4607      2288   83  Linux
         part2          4608     63999     29696   83  Linux
----------------------------------------------


Now when I increased this to 4 partitions,
grub couldn't access the filesystems on the
last 3, probably due to some offset bug someplace?

======== Bad ==========================

grub> device (hd0) /dev/loop5
grub> deometry (hd0) 1000 2 32
drive 0x80: C/H/S = 1000/2/32, The number of sectors = 64000, /dev/loop5
   Partition num: 0,  Filesystem type is ext2fs, partition type 0x83
   Partition num: 1,  Filesystem type unknown, partition type 0x83
   Partition num: 2,  Filesystem type unknown, partition type 0x83
   Partition num: 3,  Filesystem type unknown, partition type 0x83

--- corresponding fdisk output ---------------

2 heads, 32 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes

         Device Boot    Start       End    Blocks   Id  System
          part1            32       511       240   83  Linux
          part2           512      4607      2048   83  Linux
          part3          4608     34239     14816   83  Linux
          part4         34240     63871     14816   83  Linux
-----------------------------------------------

I was able to get 2 of the partitions readable by
changing the sizes a bit, but this doesn't suffice
for my needs :-(

======== Medium ==========================

grub>     device (hd0) /dev/loop5
grub>     geometry (hd0) 1000 2 32
drive 0x80: C/H/S = 1000/2/32, The number of sectors = 64000, /dev/loop5
   Partition num: 0,  Filesystem type is ext2fs, partition type 0x83
   Partition num: 1,  Filesystem type is ext2fs, partition type 0x83
   Partition num: 2,  Filesystem type unknown, partition type 0x83
   Partition num: 3,  Filesystem type unknown, partition type 0x83

--- corresponding fdisk output ---------------

2 heads, 32 sectors/track, 0 cylinders
Units = cylinders of 64 * 512 = 32768 bytes

       Device Boot    Start       End    Blocks   Id  System
        part1             1        72      2288   83  Linux
        part2            73       137      2080   83  Linux
        part3           138       570     13856   83  Linux
        part4           571      1000     13760   83  Linux

-----------------------------------------------

Any ideas?

thanks,
Pádraig.