Here's the latest -

What I think happened was that a user tried HOdling before his chain was up to date. This transaction had a maturation block that was already in the past and when miners tried to process that transaction, it caused them to crash rather than just add the transaction with 0 interest.

I've included an emergency fix in the master branch that should fix this issue, although it's a little bit difficult to fully test. I recommend immediately updating while we look at issuing a point release.

Thanks to everyone for reporting the problem and especially Optiminer for the specific bug report and fix.