They had been using the program for about a month following an upgrade, but the program had suddenly failed to load that morning.
They had uninstalled the program, reinstalled, repaired, and everything was saying the program was fine except it wouldn’t open.
The error message they received was:
There is a handy little tool on Technet called Autoruns, which shows you programs which are configured to run at bootup or login, so you can see what is blocking the program from running
After running Autoruns on the machine,(you can download Autoruns here) it was quite obvious that the problem was due to a program which had been downloaded the previous day that was blocking AutoCad 2015 from running.
Once loaded, you click on the AppInit tab and have a look at any programs listed there. It just so happened that the Trovi search and Conduit Search programs had been installed the previous day along with a program the user actually wanted.
All programs were removed, and as if by magic, AutoCad 2015 loaded without a problem. Really quick fix and worth knowing as AutoCad requires local admin rights on the machine for the end user if you have different fonts etc, which means these kind of problems due to packaged malware are going to be on the increase.