I am running PG 3.050 and Bart's PE Builder 3.0.33 with WinXP Pro SP-2. When building the BartPE ISO file, the builder executable (pebuilder.exe) fails to unload the temporary registry hive (petmphive). This occurs even if all permissions are granted to pebuilder.exe. Enabling learning mode is of no benefit, and no PG alerts occur in any case, which is strange. The exact error thrown by the builder is: Code: Error: closeHive failed: RegUnLoadKey (key="PEBuilder.exe-C:/bartpe/petmphive") returned error 0: Access is denied. Additionally, other errors occur, including this one: Code: Error: addFromInf failed: RegSetValueEx "AppInit_DLLs" returned error 2: The system cannot find the file specified. Line=1327 Key="Microsoft\Windows NT\CurrentVersion\IniFileMapping\win.ini\Windows" Value="AppInit_DLLs" In short, the only way to get successful builds when running pebuilder.exe is to totally disable PG protection before running pebuilder.exe. Also, if the petmphive hive is stuck open, you will have to unload it manually.