Problem 13: unclean shut-downs

This is a very appropriate problem number ;-) Once every 3-4 shutdowns my KDE refuses to close - it just seems to sit there doing nothing; all windows by KNotes are gone, but other processes such as kio_imap (remained of Kmail) or even Konsole still run in the background. If I switch to a text console and reboot (using either crtl-alt-del or reboot command), everything seems to go well till almost the last minute when it suddenly prints something like
"oops... could not unmount /: device or system busy"

I can't see this in the log because the logger shuts down before that. My computer turns off immediately after, and then replays hundreds of transactions with ReiserFS. Nothing suspicious appears in the log before the logger quits.

I checked my hard drive with smartctl, and it reports that my hardware is OK (of course, it could be wrong). The problem is not easy to reproduce, either, so I am now living with my fingers crossed that it does not kill my hard drive one day.