1. The most common beginner problem is certainly the failure to set your monitor to the 16 bit mode. This is required on virtually every system regardless of how good it is and how recent it is. Go to blank area of your desktop, Right click, go to Personalize, go to Display Settings, go to Colors in the lower right corner of Window, select 16 bit, click on Apply, wait for screen to change, then select OK.

Failure to do this will result in the Activity Editor crashing as soon as you attempt to mark anything along the tracks.

2. The second most common beginner error is improperly placing what are called "loose consists." A loose consist is sections of cars, an entire train, or even just one car or engine that is placed on a track as a stationary object for the start of the activity. Loose consists can be moved by the player train, but not by AI trains.

The first type of improper placing happens when the consist extends beyond the end of track on which the consist has been placed. This happens all the time by beginners. When marking a spot for a loose consist, the consist will always extend back toward the end of track if it is a dead end track. To avoid this, simply left click on the first rectangle of the consist where the circle exists, hold your left mouse button and drag the consist away from the end of track until you no longer see anymore rectangles popping into view.

The second type of improper placing happens when your loose consist extends into or is part of the path the player train or AI train has been set to follow. In other words, one of those trains will crash into your loose consist. MSTS will detect that and not allow it to happen. You can set the player train path to connect with a loose consist by placing a reverse point near where the player train will make contact with the head of the loose consist. MSTS will not let you make a path that will crash into a previously set loose consist.

The placing of loose consists can be checked in the Activity Editor, by clicking on Tools at the top of the AE screen, and then click on "Verify Starting State". However, this has to be done prior to making any other change to the activity that you are working on. MSTS will then inform you if anything is wrong.

A solid indication that you have an improperly placed loose consist for which you did not verify is when you start to play the activity and it crashes before it even totally loads.