Speaking of bug fixes

Nullable object must have a value.
at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
at System.Nullable`1.get_Value()
at Supremacy.Universe.GalaxyGenerator.GeneratePlanetsWithHomeworld(StarSystemDescriptor system, Civilization civ) in C:\Documents and Settings\mikest\My Documents\Visual Studio 2008\Projects\Supremacy_2008\SupremacyCore\Universe\GalaxyGenerator.cs:line 533
at Supremacy.Universe.GalaxyGenerator.PlaceHomeworlds(IList`1 positions, IList`1 starNames) in C:\Documents and Settings\mikest\My Documents\Visual Studio 2008\Projects\Supremacy_2008\SupremacyCore\Universe\GalaxyGenerator.cs:line 468
at Supremacy.Universe.GalaxyGenerator.GenerateGalaxy(GameContext game) in C:\Documents and Settings\mikest\My Documents\Visual Studio 2008\Projects\Supremacy_2008\SupremacyCore\Universe\GalaxyGenerator.cs:line 178
at Supremacy.Game.GameContext.Initialize() in C:\Documents and Settings\mikest\My Documents\Visual Studio 2008\Projects\Supremacy_2008\SupremacyCore\Game\GameContext.cs:line 334
at Supremacy.Game.GameContext..ctor(GameOptions options) in C:\Documents and Settings\mikest\My Documents\Visual Studio 2008\Projects\Supremacy_2008\SupremacyCore\Game\GameContext.cs:line 315
at Supremacy.Game.GameContext.Create(GameOptions options) in C:\Documents and Settings\mikest\My Documents\Visual Studio 2008\Projects\Supremacy_2008\SupremacyCore\Game\GameContext.cs:line 301
at Supremacy.WCF.SupremacyService.DoStartGame() in C:\Documents and Settings\mikest\My Documents\Visual Studio 2008\Projects\Supremacy_2008\SupremacyService\SupremacyService.cs:line 550
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
Do you have any idea to the reason for this one, i'd have thought it was due to changes via the editor as thats all i've really done, but as i can't tell whats causing it i can't fix it lol.
Regards Wolfe