I have configured our SCCM R3 for unknown computer support.
The Task Sequence I am using is mandatory for the Unknown Computer Collection.

When I PXE boot I got an dialog saying:

'name of task sequence', will run on this computer in 180 seconds.
Windows could be installed on this computer and all data on this
computer could be lost. Select 'Cancel' to stop the installation, or
select 'OK' to proceed immediately.

How can I remove this warning?

Best regards,
John.

You could remove the mandatory advertisement and make it optional for one?  I personally would not make this mandatory as you could potentially reimage machines by accident.

We want to use mandatory so that you only have to press F12 (Boot on LAN) and then the computer will be fully deployed.

In our task sequence we run a script which checks if a given computer exists in a specific database.
If it does and is allowed to be reinstalled then the deployment will move on, otherwise a warning is displayed and nothing happens to the computer.

this  might work for PXE also, please test it and let me know,

When using the SCCM 2007 CD boot image to deploy operating systems, the default behaviour is to show the deployment wizard, even if you have a mandatory advertisment. If you want to automate this, the set Unattended=true in the \sms\data\tsmbootstrap.ini file before burning the iso to a CD.

Any way to remove this??