Fedora 11 upgrade: "/dev/sda1 not cleanly unmounted" recurs after fsck
I've got Fedora 10 installed on my Lenovo ThinkPad T61 x86_64, and I'm trying to upgrade to Fedora 11.
The yum upgrade, yum install preupgrade, and preupgrade steps went fine. My grub boot menu is showing the Fedora 11 Upgrade line, as it should.
But if I boot into the Fedora 11 Upgrade, I get an error box: /dev/sda1 not cleanly unmounted, reboot and let the device be cleanly unmounted.
I've now several times rebooted into Fedora 10, at runlevel 1, and I've run fsck, and also e2fsck. I think my /dev/sda1 is clean as a whistle, especially given that Fedora 10 happily boots normally.
But when I boot into the Fedora 11 Upgrade, I still get the /dev/sda1 not cleanly unmounted error.