I had an issue with my browser that was continuing to add time to me.
From what I've seen (um...does admitting all this verify my addiction?

) you don't actually gain time from leaving the board on, as I do, in fact, leave the "home" page open. It doesn't add time to your totals unless you're browsing the board.
I figure there's between 2-4 days worth of error on my total.
I got such a high total due to the fact that when the board switched over to this software, I was on doctor's ban from work, so had nothing to do but peruse the board (read A LOT of old posts from pages back) and start laying out a CP.