RE: Help Harness lines
If your line comes out of the hook, you don't have your lines short enough, or you are not really committing all you weight to the harness.
Raise your boom, shorten your lines, take more weight off your board.
I use Reactors with both waist and seat harnesses and I have never had this problem unless I had my lines set too long.
Since I use the Sailworks "Quick Tune" adj. harness lines, I can fix this problem "on the fly".
Hope this helps,