Ultrabook means an Intel processor unfortunately, but it is what it is...
Nautilus quit opening a few updates after upgrading to 14.04. For those going umm, "nautilus"? It is the file browser, or "Files" icon in your apps.
dmesg shows something like:
traps: nautilus[pid] trap invalid opcode error:0 in nautilus[400000+152000]
Without having the time to go super deep on this, I simply reinstalled, and it appears to be working again.
Try reinstalling nautlius if you run into the same thing, with:
sudo apt-get install nautilus --reinstall
I'd love to know if anyone has the real answer for what is going on here.