Comment 6 for bug 709952

That's odd. Did you specify '-k all'? Maybe you do have a problem with the root.disk. This is what I suggest - use this tool http://ext2read.blogspot.com/ to recover any important data you have off the root.disk, and then reinstall.

If you can't view the root.disk using that tool it may be corrupted in which case you can boot a live CD and fsck it as described in the wubi guide: https://wiki.ubuntu.com/WubiGuide#How%20can%20I%20access%20my%20Wubi%20install%20and%20repair%20my%20install%20if%20it%20won't%20boot%3f (butdon't fsck it if you've already mounted it)