[Armin]

A path reference that GCA probably had stored is likely different now. You can check out the GCA.INI file manually to see if you can see it and fix it. It's found in the "%AppData%\Steve Jackson Games\GURPS Character Assistant 4" folder.

Or, you can run the GCAClearAppData.exe in your install folder, which will remove all your options and settings, and will likely fix things. At the expense of all your settings.