There are two things that may help you out with this problem:
1) Check with Toshiba to see if there are any AMT firmware updates available for your A10's. 4.0.8 is an older firmware version and there have been a lot of fixes introduced in later 4.x versions.
2) Try manually unprovisioning the clients in the MEBx before you have SCCM try and provision them. AMT will stop listening to provisioning requests and close its ports after some time. If this fixes the problem there are automated ways to "wake" AMT up to be provisioned that we can discuss here.
1) I am running the latest firmware version available on Toshiba, which is from 2009 (very old...). I have checked the site and called support. Do you know if Intel has any update available to this firmware?
2) I have done (several times) the manual Full Unprovisioning on these machines. After the unprovisioning the the only thing I do is Insert my internal CA thumbprint and restart machine, and check logs on SCCM.
You can check if at the end the machine is in listening mode for provisioning, execute the ZTCLocalAgent.exe, that you can find in the latest Intel AMT SDK, run the following command:
It should show you that machine status is "In Process", if not try:
After that, see if SCCM is able to provision again.
If ZTCLocalAgent is already showing that machine is "In Process", see if Windows Firewall is enabled (if enabled, try disable);