I'm currently representing myself in a landlord tenant matter, and the first time that I appeared on the matter, the judge who is hearing my case made it pretty clear that he knows the attorney who's representing my property management company. Later that week, I saw the attorney having lunch with the judge at a restaurant in town. What are the rules concerning a judge presiding over a case in which he has a social relationship with one of the attorneys?
 
The Rules Governing Judicial Conduct require judges to disqualify themselves in any matter where their impartiality might be reasonably questioned.  Whether the bias is actual or perceived, the judge is at least required to disclose the relationship that he has with this attorney, and in almost all cases should disqualify him or herself if the judge is "close personal friends" with the attorney.  Judges have, in fact, been sanctioned for presiding over cases involving friends.
 
Only if the judge truly believes that he or she can remain impartial, and only if the judge discloses the relationship and the parties consent, is it okay for the judge to continue to preside in such a case.  In your case, it sounds as if this social relationship, which if nothing else creates an appearance of impropriety, is something that the judge should have disclosed on the record.  If he in fact has a close relationship with the attorney, he or she should have disqualified him or herself.