> 
> Symptoms: system crashes leaving filesystem not unmounted cleanly.  Fsck 
> -p runs and complains that it can't do the job, run manually;  run 
> manually manythings seem broken (the whole of my /usr partition ended up 
> in lost+found); forcibly run fsck again and the file-system still seems 
> broken (this is repeatable).  Back off to old kernel; fsck fixes disks ok 
> (though they are still messed up by the first fsck run).
> 
You are not alone. I lost my root filesystem in an incident similar to this. I 
would have sworn that I was working with an fsck and kernel that were in sync. 
However maybe I caught the anoncvs server at the wrong moment. All I can say 
is that its a good thing I take backups :-). In my case fsck was throwing 
Segmentation faults as well as failing to fix the file system. I have been 
trying to figure out what was going on so I could file a PR.

Mike