if you have it will screw you the entire map, when you send it to dropbox.
Well i just checked through my files and my VMF is only 2kb when it should be 6,000 odd. It appears hammer crashed whilst saving my file.
\o/
Lost about 5 days work.
Fix.
I over wrote the VMF with my VMX (changed the VMX to VMF through notepad) so i got it all back.