kde crashing

[Richard Horvitz <rhorvitz ececs uc edu>]

I've turned over a new leaf and am not working as root all the time
anymore.  I was on as a user for awhile, then I logged out (of kde) and
logged on as root.  Then I logged out (from kde still), intending to log
back in as the user, but there was a slight 'sproing' sound in the
speakers after which the screen went black and the computer stopped
resonding.  Am I doing something wrong?  Is there a known bug here?
And what am I losing when I reset and it finds various problems (which it
fixes, apparently) in the file system as it boots?
  Thanks,
    Richard