if you went from 30.xx to 40.41 (or higher) there is a little hang up. It's now been fixed. It worked for me, 40.71 didn't work right before I found this.
I went from 29.42's to 40.41... no problems other than UT2003 has some glitches. my 3dmark2k1 score went from 11727 to 12642 .. are the 40.71 drivers any better?
40.71 is still quirky. It doesn't show the highlighted "new posts" envelope at OTC quite a bit, here ocassionally. Other than that, I see no difference & benchies are mostly the same.