Question : this computer is in use and has been locked

Ok, I have seen this question before but my situation is slightly different.

I'm working with a Windows 2003 R2 Domain Server & a mixture of Windows 2000 Pro & XP Pro Workstations.  All systems have the latest service packs & updates done to them.

The problem is this.

I have recently implemented 4 Dell laptops with XP on them.  They are being used to run Smartboards in 4 class rooms.  The Smartboard is connected to a USB port & the projector for the board is connected to the external video connector.  I have turmed off power saving & screen saver by editing the registry for the user that runs the Smartboard.  Even after doing all this after 60 seconds the screen goes to the little windows Icon floating around & when you touch a key or move the mouse it comes up & tells you this computer is in use and has been locked.  Only ____ or the system administrator can unlock it, etc, etc.  This only occers if I am connected to the domain & log on to the domain or if I am disconnected & I logon to the domain using cached credentials.  If I logon using the local machine setting with a local user name & password it works fine.  It never locks me out.  

Here's what I have tried to resolve the issue:

I have confirmed that the doamin is not doing this through group policy.  Even still I set the timout on this to 24 Hours

I have checked the local group policy on the laptops.

I have checked the desktops in the network & they are not locking after a minute.

I have disable the screensaver in the registry for the user in question.

Even though I have done this I set the screensaver timout to 24 Hours.

Yet is still locks up after 1 minute.

Please help.

Answer : this computer is in use and has been locked

Create a new Organizational Unit in the active directory
Block GPO inheritance on this new OU
Move the laptops to this new OU
Reboot the laptops and test