Registry Compactor usually shows 11 with my Vista and XP Pro systems.
With Vista:
* You get 2 more for each additional userid that is still logged in (probably with XP too)
* Sometimes (rarely) the COMPONENTS hive does not show
* Sometimes a schema hive shows
* At a given moment in time, what will show is reflected by this registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\hivelist
I have never seen it show only two as reported here. I wonder which two they were?