When you export the SYSTEM hive of the registry to save it, and subsequently import it to restore some values, the import terminates and you are warned against product tampering?

When you export the SYSTEM hive, the REG file contains:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ProductOptions\ProductType

Attemps to import anything into the ProductOptions subkey, results in the warming.

Simply remove all references to the subkey from the REG file.