First some setup. I am using AG to build an activity on the Clovis Sub route, going EB, using the template obtained here (as recommended by the example video) I am setting up max 20 cars to handle, 10 max setout and pickup. Picking up from Belen yard (all selected), dropping off in Abo (all selected). All goes well until I'm proceeding EB off the Sais siding track, merging onto the single track portion at MM 875, where I am signaled to stop and wait. A few minutes later I crash out to the "train.exe has encountered an error...blah blah" window. If I reload the activity from the last save point, it will predictably crash at the same point. Sometimes I'll catch the glimpse of the AI train in the distance before it crashes out.
I have made no consist modifications and have checked everything thoroughly with Route-Riter and ConBuilder (which I broke down and bought). I AM using MSTSBin version 1.7.051922.
I read somewhere that some people were running into issues with too many wagons in the simulation (this activity loaded some 200 or so in, if I recall), but I don't see anything here about anyone having that problem.
Has anyone else grappled with this issue yet, and if so have any suggestions?
And, is it just me, or is MSTS about the buggiest thing we've seen out of Redmond since Windows 3.0?

Paul