Any reason when I add a Circle, Cylinder, etc. that I can not change the values in the tool shelf anymore(they are grayed out)? FYI F6 doesn’t work either. 
Anyone else experiencing this?
Blender 2.71/2.71.6 32-bit
@IkariShinji: Thanks so much, I didn’t see that! 
Next question, how the hell did that happen? I don’t recall touching that setting. 
Did you upgrade recently from a previous version?
This seems to happen to (some) users migrating from 2.70a to 2.71 - perhaps some bug in importing/converting the preferences?
I had gone from 2.70 to 2.71 whenever it came out, and the same thing happened, I just never said anything. But I think you’re right, because recently I got rid of a bunch of older versions and test builds, and only kept 2.70(with a load of addons I’m too lazy to put in 2.71). Then I downloaded a 2.71 release, but somehow, when converting preferences, it shut off the same thing in 2.70 so the menus were grayed out in both versions. That’s a strange bug indeed.
Thanks again for the help!