I too get 'Ext2 partition has unrecoverable system error, do you want to continue or go back and repair problems?', even though fsck reports clean/OK immediately prior to start of install. This happened in breezy & dapper, as I can't even get the installer to find any partitions in current edgy FTP install.
-- file system has an incompatible feature enabled https://launchpad.net/bugs/37137 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs