Did you consider that the error message might be correct? I just looked up the permissions on that key on my Win7 x64 system and guess what I found: only the TrustedInstaller has write permissions.
I have created a Wiki page describing the reason:
http://setacl.wiki.sourceforge.net/Error+Message+-+The+data+area+passed+to+a+system+call+is+too+small+-+A+privilege+could+not+be+enabled
I hope this helps.
This is very probably not a bug. SetACL's error message "A privilege could not be enabled" means that for the requested operation a privilege (user right) is needed and could not be enabled. The reason for that is that the user account the program is run with does not hold the privilege.
There _are_ differences in the default privilege assignments between client and server operating systems.
This is not a but in SetACL, but in the underlying Windows API. For a better way to achieve your goal see:
http://setacl.wiki.sourceforge.net/Frequently+Asked+Questions.
