Classic and (null) run at startup


Hello everyone, Recently our mac running OS 10.3.9 has had an intersting problem. Classic attempts to run at startup, even though the options in preferances tell it not to run at startup, and even to warn. We also notice that something is hogging all of the computer's processing power. When i open the activity monitor there is a process listed as (null) using upwards of 90% CPU usage at times. If i quit either classic or (null) the other one goes away as well. This only happens on the one user account, but if at all possible we would like to avoid creating a new user (about 50% of the hard drive resides on this user's Desktop in one form or another, and it is the only account ever used on this computer. I have more experiance fixing problems such as this on windows computers, and am at a loss for what to do here.

Any help would be appreciated
A guess:
Check the users 'System Preferences' 'Accounts' 'Startup Items' list. See if 'Classic Startup' (or equivalent) is listed. If so, click on it and then the '-' icon button.

A fact:
In each users 'Preferences' folder is a 'ByHost' folder ('~/Library/Preferences/ByHost/'). Look for a 'loginwindow.XXXXXXXXXXXX.plist' (where the 'XXXXXXXXXXXX' portion is your Macintosh'es Mac address) file in the 'ByHost' folder.

What to try:
If the 'loginwindow ... plist' file exists, drag the file to the 'Desktop' and restart (reboot) the Mac. Does 'Classic' now automatically launch?
Either way, delete the file.
Or - there is a Classic program set in the users startup items or login items. Check the list of those programs to see what is starting up when the user logs in.