I believe it's bug. I have test with my system, when i try to backup the following key
1: HKEY_CURRENT_USER\Software (This key is work well no error found.)
2: HKEY_LOCAL_MACHINE\SOFTWARE (It's error with this key.)
For HKEY_CURRENT_USER\Software it's can backup with no error event all subkey, but
HKEY_LOCAL_MACHINE\SOFTWARE it's content the large subkey in HKEY_LOCAL_MACHINE\SOFTWARE\Classes , the XceedBackup always error with large number of subkey, i know that i can fix error by providing all subkey, but when then subkey contents hundred of keys it's not natural way to do this.
I have purchased an Xceed Datamanipulation and believe Xceed's developer can fix this bug.