Yup, you have dotqueries turned on. Go to your admin Cpanel and turn off "Use dot icons" -- I did point that out as a problem in my previous post

It is trying to join the post table twice. You'll have to write an exception to check if dotqueries is turned on and if it is, change the join again.
I don't use the dots since I didn't think the join was worth it.. but for me, the join is worth it for the preview.