I would look at the printer setup as it may be looking to print from a printer that it cant recognise or find

unfortunately I have never printed reports from CAD-Mep but I just tried it and it worked just fine for me

usually on Cam or Est it has a similar message when the default printer is incorrectly setup or unrecognised and usually happens when I am on a different Database at home as it cannot find default printer from work

Have you tried running reports from Cam duct or Estimator (if you have)?

sorry if that's not much help but its all I can think of