Is Firefox causing the sleeping MacBook problem?

There are some things in the tech world I seize on right away, and others I refuse to upgrade on. Firefox 3.6 was one of those I stuck with. I had tried the FF beta, but found its tab handling overbearing, and refused all updates. And then a couple of months ago, Mozilla made Firefox v. 11 a "minor update" for 3.6, and I went through a quiet upgrade. I put up with the tabs, got used to the new interface.

And that was, coincidentally, when the problems started. I'd take out my laptop to write a blog post (or maybe something else), but it wouldn't start. I'd press the start button to wake it out of hibernate mode. Although with a 90% charge, it had no business going there. But then half the time the Mac would go through a full restart. It's a three-year-old MacBook Pro. Not brand new, but shouldn't be entering senility yet.

Yesterday I saw a post on this on a now-forgotten feed. The conclusion was the "check for updates" feature of all programs. The only one I always run that I can think of that does this is Firefox. So I went into Preferences/Updates, chose "Never check for updates", and we'll see if that fixes the problem.