Do you have Large Address Aware installed? The game was written to only recognize I think 2Gb of RAM. With LAA, it will allow the game to recognize your RAM.
You can find it here
http://www.subsim.com/radioroom/down...o=file&id=3634
How big of swap file or virtual memory do you have? The default is "Let Windows decide." Change it to something large. You have Win 8, so I can't help you on how to change it.