Auto capitalization in Lion

This is a system wide issue. It happens in Pages, Mail, TextEdit, Stickies, Safari -- basically every Apple application in which you enter text on Lion.

I asked this before a few months ago, and thought I had a solution, but I'm wrong and it's driving me nuts. Significantly, it DOES NOT occur in Word.

If I type a period somewhere in the middle of a sentence, it automatically capitalizes the next word. As an example, if I type this:

John Doe Jr. Bought a new car

It capitalizes the B in bought by itself. That is incorrect and I have to go back and fix it.

It fixes itself if I backspace and correct. So, if I write

John Doe Jr. bought a new car

I initially get the capital B, but then I can go back and fix it. Then, even if I choose to use a different word after the period, the first letter will be lower case, not upper. This auto-capitalization only happens the first time, in other words.

There does not seem to be a system wide preference for it and none of the application preferences work. It's driving me up a tree.

Can anyone make a suggestion?