No keyboard at login window after logout

Question

Hello all,
I'm just starting state testing and have been presented with a problem.  When a student logs out of a machine in order to log into the testing account the login window won't accept input from the keyboard.
Bacground and details:
We have labs of computers using workgroup manager and open directory for management.  In a normal lab the machine will boot to a login window.  This is so that the preferences will be refreshed before a student logs in.  The student will login as a local user (student) and procede to do whatever for the day. 
We have recently started state mandated testing.  I have set up an OD account which is very locked down and keeps the student on track while testing.  This requires someone to log the normal user out and login as the OD user.  This is where the problem arises.
About 50% of the time the keyboard will no longer funtion after logout.  No keys of any sort work. The mouse still works.  Even keystrokes through ARD do nothing.  A end user is then required to reboot the system in order to do ANYTHING.  This is not ideal for elementary kids.
From my digging in log files and poking around i noticed that the loginwindow process was hanging or crashing.  If i kill the process the login window blinks and then works just fine.  I'm sure i could write a logout script that drops a process into the background to kill the loginwindow process after so many seconds, but thats messy.  Has anyone seen this?  Any thoughts or solution? Only happens on a logout, never on an initial bootup.
I have found that 95% of these issues occur on Mac Mini's.  I can consistantly replicate the issue on a mini.  If i clone the mini to a macbook, i no longer have the problem (using carbon copy cloner).  So either the hardware is part of the issue or the clone fixed something in the process.
OSX 10.5.8
/var/log/windowserver.log  (on logout)
May 02 16:27:30  [252] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x6 not owned by caller loginwindow
May 02 16:27:32  [252] CGXRestartSessionWorkspace: session workspace exited for session 256 ( on console )
May 02 16:27:32  [252] loginwindow connection closed; closing server.
May 02 16:27:33  [352] Server is starting up
May 02 16:27:36  [352] CGXMappedDisplayStart: Unit 0: no display alias property
May 02 16:27:36  [352] kCGErrorFailure: IOHIDSetCursorEnable returns -536870208
May 02 16:27:36  [352] kCGErrorFailure: Set a breakpoint at CGErrorBreakpoint() to catch errors as they are returned
May 02 16:27:36  [352] CGXPerformInitialDisplayConfiguration
May 02 16:27:36  [352]   Display 0x41dc9d00: VirtualDisplay Unit 0; Vendor 0x756e6b6e Model 0x76697274 S/N 0; online enabled built-in (0,0)[1280 x 1024], base addr 0xb0021000
May 02 16:27:36  [352] AGCAttach: Couldn't find any matches
May 02 16:27:43  [352] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
May 02 16:27:45  [352] kCGErrorIllegalArgument: CGXOrderWindow: Operation on a window 0x2 not owned by caller SecurityAgent

Answer 1

>kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller SecurityAgent
In those cases there may be threads and/or processes trying to do things with windows that they don't own. In other words, some programmers may have goofed up a little bit someplace.
But might try the one Helpful marked post here...
https://discussions.apple.com/thread/987826?start=0&tstart=0