I should clarify my earlier answer...
Step 1 - Save As... a template to the Project Templates folder e.g "MyTemplate.cwt"
This template now works fine, but doesn't have the pretty image in the Start Screen.
Step 2 - Create the image
Create your image, and put it in the Project Templates folder (named as per the template, e.g. "MyTemplate.cwt.png")
Step 3 - Associate the image with the template
In Cakewalk, load the template and then re-save it (as a template) back to the Project Templates folder (overwrite the existing file).
From here on in, you should see your defined image in the Start Screen
Agent Phil's post in Remove Articulation Map From Project? was marked as the answer