On my I9000 (galaxy S) this just means that something has changed the filesystem withingfile-system within the phone like ext2>ext4ext2>ext4
and the current kernel doesntdoesn't support it..
Normally happens when flashing custom roms without checking the kernel requirements.... like I did :-(
The only way round it is to reflash using odin with a 512.pit512.pit
file and make sure you select re-partition..