I agree with Wolfehunter, the game is more demanding with so many addons, my Sons computer only has 1gb & he can't play with my setup, however it runs stock ok.
It could also be a problem with various other mods you have enabled, if you have a corrupt ship install, when the ship comes in contact view you can get a CTD, this applies to sound, land objects etc, but the best bet, IMO, is more ram!
