Comment 4 for bug 211760

 I was suffering from this, and it turned out to be bug #151025, or close to it. The mysterious "invalid mount option" error message that never revealed which option it complained about is gone now. I looked in GConf [Press Alt+F2 and type gconf-editor], and for FAT filesystems -- /system/storage/default_options/vfat -- the variable "mount_options" was set to:

[shortname=mixed,uid=,utf8,umask=007,exec,usefree]

I removed all the options one by one until deleting 'usefree' made auto-mounting possible again. Was this a new setting in Hardy?