This is a Vista thing, but it deserves a new topic, cause it deals with the post-SP1 situation, and therefore previous information may no longer be valid (so merging this with a Vista thread would just be confusing):
People have said that SP1 helped them run HZ on a constant basis. Windows update just downloaded and installed SP1, and no go.
What additional steps did people take to make HZ work on SP1 besides installing the update itself?