I think you may have a corrupt registry. Look in WindowsSystem32 or WinntSystem32, whichever you have, and see if you can see NTDLL.dll. If it is there, then it's possible that something has removed its registration. The other possibility is that the file has been corrupted. If your IE is still working you could try going to http://www.healthycomputerclub.com/Software/PCRescue/index.html and try their free diagnostic check; it may give you some more information. I would say your next step should be to contact DAZ, with your error message and any extra info the above site gives you, and report the problem to them. If there is a possibility that one of their install processes has corrupted your registry, they should respond positively. It's probably better not to try fixing a problem like this yourself, as it could make things worse, or at least obscure the original cause of the problem. If you have a friend who knows about computers I'd invite them round for a drink! Also it may be worthwhile running a virus scan just in case DAZ studio was not the cause of the problem.