Try setting Microsofts PDF Printer as your default printer and set it in datacad as both options, primary printer and check plot, print to that and see what happens.
May need to clear the windows print queue although if it's crashing before you are getting to send it to the printer I suspect it's not the windows spooler.
Does Datacad produce some tmp files to do with printing that could have got screwed up.
DaveR
"Life isn't about dawdling to the grave, arriving safely in an attractive, wrinkle free body, but rather an adventure that ends skidding in sideways, champagne in one hand, strawberries in the other, totally worn out, screaming 'yeehaaa, what a ride!"