[PeterM]

Not sure what you may have done with registry changes and cant help with graphics card.
If you can try clicking on FILE then OPEN if it does open then a box may appear saying "Chart Settings modified do you want to change" = click no. A box should appear with Chart Settings and Home.Sky try clicking on Home.Sky and see if the planetarium comes up.
If not you could reinstall SkyX and start again or put it up on the SB website and they will respond quickly.
One thing you may or may not know is that if you save your settings after you exit the SKYX they are saved in My Documents folder under Software Bisque under a folder called SkyX Professional Edition - this is a saved copy of your current settings.
Should you ever want to copy exactly what's on your current machine (settings etc) to a new one (or reinstall on your current) you simply copy the file SkyX Professional Edition to say a usb drive.
Now re-install Sky X on new machine then run it (this then creates the folder SkyX Professional Edition)
Open up My Documents/Software Bisque and then delete SkyX Professional Edition and now copy the one you saved to usb.
Now open the SkyX and all your settings should now be on the new install.
BUT the version you had on your old machine must be the same as the one you will copy the above folder to on your new machine
i.e Mine is 10.2.0 (build 8114) if I want to copy this to my new machine I will need to 1. Install The SkyX 2. Update daily build to 8114 then copy & paste the Sky X Professional edition folder from usb to My Documents.

I do this regularly as a backup so if the worst happens I have a starting point.