--- Operating System, Graphics card ---
Linux Mint 14, x86_64, GeForce GTX 650 Ti

--- Blender version with error, and version that worked ---
2.68a, r58536, no known working version

--- Short description of error ---
Blender becomes crashy when using the skin modifier followed by two Subdivision modifiers on the stack (two independent modifiers, not one modifier with two subdivision levels). The error primarily occurs when adding or removing vertices while in edit mode, though it doesn't always happen. Removing specific vertices or extruding new vertices from specific existing ones will consistently reproduce the crash. It is possible that there are multiple crash sources.

--- Steps for others to reproduce the error (preferably based on attached .blend file) ---
Use the provided file. The following actions will produce a crash.
A) Find any vertex located on the Y axis down the center, and remove it or an adjacent axis.
B) Extrude a new vertex from any existing vertex. If there is no immediate crash, move it around.
C) Select any vertex and attempt to move it
D) In the modifier stack, click the Hide button one of the two subdivision modifiers, then make any of the above changes. Then unhide the modifier.