So... the board is showing the last new member was a member who joined October 3rd and I know we've had new users since then.
I just created a new account just to make sure and the "Latest Member" didn't change.
If you aren't running 1.2.2, make sure you upgrade to that.
In general, this is often related to add-on cron timeouts, though there has been one issue reported with the feed importer if you have a lot of feeds. The code has been further tweaked in 1.2.3 to prevent this.
That worked. Unfortunately this became a daily routine, but I don't think it was xenforo. Our Hosting company had us down to 1 gig of ram and 1 core of the processor. We switched hosting companies on Friday and haven't had a problem since.