There were two issues that I ran into. One was as you listed, the --force command, which caused the access violation. The other was -x -w, which caused new files to not be merged to the target branch (although -x -b seems to work fine).
Thanks for your response.
I can’t be sure that this is the cause but please try running merge without --force.
There is a fix for incoming directory deletions during merge scheduled for the next 1.8 release.
With 1.8 using --force shouldn’t be necessary anyway as the old tree conflict detection problems were resolved by 1.8.0. (--force made older versions strict ignore what was deleted when applying deletes)