what you need to do is to mount your filesystem manually. You have been able to mount other partitions and their filesystems easily because they had an entry in the the "/etc/fstab" file. You can also mount it manually, once you are able to mount it manually just transfer those options to the /etc/fstab file. First you need to figure out what is the name of your FAT32 partition. Do the following:
1. login as root in a terminal
2. open terminal, and type "su"
3. type "fdisk /dev/hda"
4. type "m" enter
5. type "p" enter
6. type "q" to exit
Now that you know what is the name of your FAT32 partition you need to mount it, by using:
mkdir /mnt/vfat
mount -t vfat /dev/hdax /mnt/vfat ***************IMPORTANT************ REPLACE /dev/hdax with whatever is the name of your parition
Of course this commands only create a directory where you will mount your filesystem. You still need to figure out how to do this in a more secure manner. You have to provide some options to the mount command so a regular user, you, can access it. In other words this command allows only root to access your partition. I would recommendyou read the manual page of mount, and what options it has for fat 32 partitions.
Good luck,
pitupepito