We spent a while trying to reproduce this crash on your data files, but unfortunately we could not. The only possible suggestion is that you are running MultiChain on a very RAM-limited server, i.e. less than 256 MB.
From the next version we will distribute MultiChain with more embedded debugging information, which will enable us to use messages of the type you saw to determine which line of code the problem happened in.
In the meantime based on the loads in your data files, you weren't doing anything remotely near MultiChain's limits, so this appears to be a straightforward bug we just need to fix.