The GECK is the Garden of Eden Creation Kit. In the series, it's a civilization rebuilding kit. Allows for terraforming and repopulating the Wastes. In real life, it's the official software development kit or mod toolbox.
ETA: that's also an odd multiple of RAM. Did you recently upgrade?
If you meant 16gb, that would make sense. But 18 would actually be counter productive and hinder your performance. DDR (Dual Data Rate) works better in sets of 2. A single stick will also work.
As far as the crashing goes, have you tried uninstalling/deleting local content and trying again? Sometimes a chunk of data can get corrupted on download. It's worth a shot (unless you have a data cap).
Another option that I'm sure you've most likely explored already is running it as the Admin (right click on Fallout4.exe and click run as administrator). Usually doesn't do the trick, but it's better than waiting for a patch.
One final option I can think of is to make sure your GPU driver is up to date. Another long shot, but again, it's better than nothing.
