1. Uninstall the previous program you have installed.
Tried that.

2. Reformat your PC
Absolutely not an option. I have a working copy of this program on another PC so I'm not blowing away everything on my laptop for one app.

3. Registry cleaner
This was going to be the next thing I try. I've got a good reg cleaner that I trust, some cause more problems than they solve!!

In the error message, DLL_File_Name is the name of the DLL file that is being called.
This is my main problem, the error message doesn't state what .DLL file is missing, they couldn't possibly make this easy for me.

Runtime errors may also occur due to the existence of invalid registry entries and malware infections.
Have already run a quick spyware and virus scan but nothing was found. Will run a deeper scan over night some time this weekend.

I suspect that a registry scan may throw up some clues but I have to get my wife off of the damn thing first.

Thanks for the suggestions guys, I'll let you know how I get on when I get a chance to have a play with it.