Problem

 22:36:53 <+Psycho> C:\>ipv6 install
 22:36:53 <+Psycho> Installing...
 22:36:53 <+Psycho> Failed to complete the action.
 22:36:53 <+Psycho> Error 0x800704b8

Fix

 22:37:30 <@Byte> http://www.sixxs.net/forum/?msg=setup-228387
 22:37:35 <@Byte> esentutl /p %windir%\security\Database\secedit.sdb