I once worked on a frustrating deal that, try as I might, I couldn’t seem to close.  Complaining to a colleague who’d also done business with this counter-party, he said “oh he’s the kind of guy where if you’ve got 2 open points and think you’ve closed on 8, you still have 10 open points.”  So how do you deal with a party who takes advantage of unresolved issues to go back and re-renegotiate earlier ones you thought you’d closed out on?  Who won’t, in effect, stop negotiating?  Unfortunately, the best defense here is a good offense.  What this sounds like: “Gee, I thought we’d been making great progress here, having agreed on how to deal with [closed point(s) on which you’d made concessions].  If we need to have those conversations again, I’ll be forced to re-consider those concessions I made for you.  And that’ll of course be a set-back for everyone involved.”  Such an approach usually works to ensure forward momentum, which is important to maintain, even when one part of your deal isn’t closing as quickly as you’d like.  Check back tomorrow for another suggestion on this front.