Hi Joel,
No, I am not using JetPack, as I have heard bad things about it (slows down sites, etc.). I am, however, using the following plugins:
floating social bar
google xml sitemaps
login lockdown
theme check
w3 total cache
wordfence security
wordpress seo (by yoast)
Should I just deactivate all of them, see if it works and then re-activate one by one?
Thanks,
Marshall