I've got a small (2Gb) USB flash drive that has a slightly peculiar problem: OS X can't read it's file system, yet all other PCs I poke it into can. Windows, Linux, Android - all can read it just fine. OS X cannot.
This has been a problem from time to time with a friend's laptop as she has a Macbook Air. It was recently slightly more annoying with my own work laptop which is a Macbook Pro.
Then I figured out what's wrong.
When I first bought the flash drive, I put a 1Gb Ubuntu boot image on it. This was used to install Ubuntu to a netbook that had no optical drive. Once this was done, I wanted it to be 2Gb again; which meant recreating the partitions and reformatting. But I used partition #1 and I've heard that most flash drives use partition #4. I suspect this is why OS X is unhappy with my flash drive.
Anyone else seen this? It is extremely difficult to search for on the googles. I know the fix, of course, I just wanted to talk about it with someone.