If you see:
The following error occurred in file://path.../Adm/somefile.adm on line 62. Error 64 Help string specified more than once. The file can not be loaded.YOu click OK and then get:The following error occurred in file://path.../Adm/somefile.adm on line 6537. Error 64 Help string specified more than once. The file can not be loaded.
Most likely you have added a .adm file that was made using another .adm file. To fix this you will either need to remove the original .adm file and just leave the new one (remove the .adm file from you group policy editor) or edit the string items that use identical names. For example, you have system.adm and then made a new file will settings that are different than system.adm but you used system.adm as your starting point. Now both file use the same string variables which doesn't work. Both files might have !!WindowsExplorer and then a string definition for WindowsExplorer. The identical names need to be changed or the one of the files removed. I ran into this today when making a new .adm based off the system.adm (I wanted to add to the !!NoDrives section). Instead, I just created a new .adm, copied the stuff I needed and then made new string identifiers and strings. I replaced !!WindowsExplorer with !!HideDrives, etc. That solved this problem.