ntvdm issue

My XP machine hangs when trying to install a couple of programs. Gets to the click on install, egg-timers for a few seconds and then disappears. Task Manager shows ntvdm process running at 90+% CPU.

Similar installs have worked in the past. Two potential changes to m/c set up. One is latest patch to XP, other is installation of second hard drive. Can’t tell if either event is relevant, but it’s the only thing to have changed.

I’ve understand what ntvdm tries to do, don’t understand why it does now and didn’t previously !!

I’ve tried many things, to many to list on here and now I’m stuck, any ideas ?