Agree with Katie. If it still keep on crashing, it may be a "out of memory" problem of your computer. I would recommend cleaning all the cashed and try again.
It seems like you're hitting a resource wall.
Can you give an indication of the document size and how much RAM and free hard disk space you have?
You might want to try saving it as a .psb file. This a large format file format.
You can get more info here.
If you are able to open it, Group all the layers and Duplicate to a new document. That will lose any work paths and alpha channels. You'll be able to remake the masks from layer contents. The paths not so easily.
Another way is to select all the layers and make them a Smart Object. Double click the SO to open in a new window, and save the resulting PSB file to a new document. You are good to go from there.
I have occasionally used both methods successfully when a layered document has played up.
If it still keep on crashing, it may be a "out of memory" problem of your computer.
Out of memory doesn't crash the computer. You'll just get a nice, polite message to that effect, and the operation stops.
I'd go even further: a file in itself can't crash the system. It has to be because it calls on some component, usually video driver related, which then crashes your computer. The file isn't the cause, just the trigger.
Agree with that!