I'm having the same problems but... my drive is a whopping 160GB and it still is not saving changes (it's a Memorex Ultra TD USB2.0). I went to all the trouble of downloading and configuring packages only to find they are not there on the next boot.
I believe the problem may have something to do with Mint thinking that it is running from a CD (this also will happen on a normal flash drive, so it is not just because of the type of drive I am using). I am using FAT32 so that I can use the drive if I need to switch to Windoze for some reason.
In Ubuntu there is some command that you add to the start-up script to tell it that we are running a "live" copy and not a CD, but I have no idea how to do it. Should probably mention that I had exactly the same problems in Ubuntu as well. I installed that first, and then switched to Mint.
I have absolutely no desire at all to install the OS onto the internal hard drive. Ubuntu and Mint both make the assumption
that we will eventually want to install them internally. I certainly am very attracted to the idea of being able to have a portable OS that I can just plug into another computer and use anywhere, so that everything is just the same no matter what the location. Installing it on the computer would not achieve that result, so I really don't want to do that.
Nev : Edit:
wanted to add, I think I have discovered some evidence to suggest I am right in my supposition that Mint thinks it is running from a CD even when it is not. This is because it is reporting that it has something like 393MB free, which I take to be the difference between the actual size of the installed files and the maximum capacity of a standard CD.
Strangely, while Ubuntu can declare the Memorex disk as a separate entity to the file system, Mint does not seem to have this ability. Ubuntu and Slax both are able to allow normal access to other parts of the disk, but Mint not only does not allow disk access, it does not even seem to have an awareness that the disk exists.Another Edit:
I renamed "isolinux" to "syslinux", so maybe it no longer thinks it is a CD. Because for some reason Ubuntu (and probably Mint) does not recognize a USB HD as a USB Flash Disk - a trait that seems to be unique to them - I can't set the persistence file using the "create USB disk" tool. Does anybody want to instruct us with information on how to manually create a persistence file and then tell Mint where to find it (if indeed this is necessary)?