Hi Tonylx4 !
When you said "It's only DG-IV nothing else", you're saying that you only have the DG-IV as add-on in your Orbiter ?
Also, did you change your PC or your Windows since the last time you have played with the DG-IV ?
Finaly, what lags do you have ? Only drop of framerate, graphic problems, a CTD (Crash To Desktop), a Windows BlueScreen ?
With those questions answered, we'll be able to help you
.