Tactics trainer rating changes changed?

Up until yesterday I think, the biggest change I'd seen was probably about 15, 16 or maybe 17. I can't really remember exactly.

Then, yesterday, suddenly I went down 31 in one go and it seems that's happening quite a bit now. Is that going to stay like that from now on?

Wait, do you mean to your rating?

As you get a higher rating in TT, occasionally you will get a problem rated far below you.  Miss one of those and you'll lose points big time.

Sorry, yes, I meant my rating.

Ie. I was merrily doing puzzles around 1500 rated, missing one, getting another and then boom went down 31 points. And another 25. And now I'm down to 1391.

Now, that's my mistake, I'm not complaining about missing puzzles or anything. But the wild swings seemed a bit random. Perhaps baddogno got it, especially given that the big swings only happen downward. It just surprised me :) 

Also, a bit more feedback related perhaps:

There used to be an interface to see all the past problems you've done. I can't seem to find that any more and I found that quite useful. Am I blind, or is it the browser I'm using (Opera), or was there a reason that feature was removed?