Have you just installed PTC’s Mathcad 14 on 64-bit Microsoft Windows 7 Professional only to receive the strange and not so informative error message “Unable to create 12.0 engine factory” when trying to run the software?

Then maybe this thread will solve your problem: http://communities.ptc.com/thread/14720

In my case I already had the necessary prerequisites in place, and only had to perform this command from a privileged command shell:

"C:\Program Files (x86)\Mathcad\Mathcad 14\mathcad.exe" /register