It could also be a simple permission issue, depending on how the filesystem was mounted. chown/chgrp doesn't really change anything about it, as FAT32 does not have the capability to support Linux permission and group ownership system. These permissions are determined at mount time. So if you're not the owner of those files it was simply mounted wrong.
User friendly distros like Ubuntu usually do the right thing by default; on other systems, you may have to create an fstab entry so the user will be allowed to mount, and actually mount it as user then, or supply the proper mount options.