FSX freeze up problem - Possible causes?

Make sure you have enabled only addon scenery that you will be flying over during your flight plan. If you have any photoscenery around the world, it will load no matter whether you are flying over it or not. I use SceneryConfigEditor before each flight and make sure I only have what I need for my intended flight plan. Also, turn off Autogen and see if that makes a difference. I doubt ASN is going to cause the problem unless you are using an external program which has themes like REX or FEX for rendering your clouds, etc.

Best regards,