I have been using this for only about 2 days now, and I am already in love with it. :-*
I have long been a user of http://www.joesgoals.com/index.cfm, but this is a lot more powerful as it allows me to modify my behavior both on the reward and the action side.  EG: I always manage to talk myself into a candy bar in the afternoon, but I skipped it today because I wanted to spend the points elsewhere, and setting up the software didn't earn me any points, so I was short on points.  I have heavier rewards for things I like doing less but should be doing more, in hopes of setting up new habits.  This is definitely a winner.

Carol, I thought I was going completely crazy.  My symptoms are not as bad as yours, but my firefox will occasionally crash when I click a link.  It appears completely random.  One second I am clicking a link and the next second I am looking at my desktop.  I can't manually close the software that quickly.  I am certain that the trouble must be in a conflict with an extension, but, like you, I only have the trouble very intermittently.  So, you are not crazy, and neither am I (or at least this is not evidence of it :) )