In the last 24 hours Chess Mentor Scoring has become punitive for me. At the outset of a lesson huge deductions are made for no apparent reason. Even without touching any of the hints or making a wrong move my score plunges downward 40% and worse.
This is little fun and very discouraging. 
I've worked hard for in gaining Mentor Lesson Points. I don't like seeing them evaporate unfairly.
It is discouraging to be faced with a Mentor Score Bar showing me at 43 points at the outset of a lesson. I had a 1 1/2 months of Mentor Lessons before the Mentor Score Bar turned against me. My happiness with Mentor Lessons ended for me on Friday June 12, 2010. Now I am hurting.
I sent an email off to help and support. I hope to arrive at a solution. I sent in a second email to Help and Support today.
After a little bit more suffering the Mentor Score Bar has resumed its characteristic fairness to me. I am slowly regaining some of my lost points. On reflection I now have a sound hunch regarding what went so wrong for me.
A week or so back while doing poorly with certain lessons I exited in order to avoid significant point losses. Mentor later took me back to the abandoned lessons with the Score Bar as it was on my exiting. Now I come to understand that there is no way to flee from point penalties by exiting before concluding a Mentor Lesson. It is best for me to accept my punishment as Mentor meters it out to me. Here forward I must see each lesson through to its end. 
I believe this bug is the reason why the Chess Mentor ratings are out of kilter and Adaptive mode does not work as it was designed. It’s a great concept and the Impact of the Actions, according to the Chess Mentor Help, looks about right. Maybe they could be tweaked over time. If the bug was fixed I believe that both the Student and Lesson ratings would settle down and reach a satisfactory equilibrium.
I've heard talk of coming upgrades to the Chess.com site. Perhaps the impending upgrade/s will solve the bug.
For me my whole problem was in getting to know Mentors Score Bar better. With a better understanding of Mentor Scoring I've become as happy as a bug in a rug.
Hopefully your irritation with Mentor will resolve soon.
According to the Chess Mentor Help, each lesson you complete should receive a new rating after you complete it. This is not happening.
Chess mentor, even without the score, is still a great training device. They will get it fixed. I am always amazed what Chess.com does with about 6 staff members (and a handful of part-time employees and some volunteers).
But I agree -- 40% is a problem. I think I will stay away from Chess Mentor for awhile. And you are right. The SHOULD send out a pubic notice when it is fixed.
I apologise for the caustic comments I made in my post on 20th June 2010. The people running this site are genuinely nice people.
I have edited my post suitably.
I would like to see Mentor greatly expand two courses, 1. The Combinations of Mikhail Tal and 2. The Combinations of Alexander Alekhine. They are both really fun to play and are sources of wonderful learning.
A couple of points; When the scoring seems to be unreasonable, I have to make myself remember that it is not a competition. It is an example of a master's game and the teacher is trying to lead us through it, while examining our ability to analyse and to understand the carefully worded hints. It seems not to be the use of hints that drops the score, but the degree to which we understand them and follow them intelligently.
Also, I am fairly new to the game, and have found that it is revealing, of my own limitations in projecting analysis, that, when given a multiple choice of options I almost invariably choose the wrong ones. Because of this, my respect for the game and for those who master it remains high.
There seems to be a bug with the scoring of Chess Mentor (Per My Score bar). The score often jumps to a higher percentage when it should decrease to a lower percentage or not move at all.
For example: when accessing the Subtle, Strong and Direct Hints; making a wrong move and hitting the Try Again button; making an alternate correct move; hitting the Key Pieces button and getting the message “Key pieces not shown for this lesson” – the percentage score increases; etc, etc.