Hi,

--- Short description of error ---
Blender crashes when I try to go into Edit mode, after applying Decimate or Remesh modifier.

--- Blender version with error, and version that worked ---
It crashed with 2.65 and latest SVN.

--- Operating System, Graphics card ---
Debian AMD64, AMD HD6850


--- Steps for others to reproduce the error (preferably based on attached .blend file) ---

1. Add a UV-Sphere
2. Tab into Edit mode and select some faces (but not all)
3. Tab out of Edit mode, add a Decimate (or Remesh) modifier.
4. Set Decimate parameters to: Collapse with Ratio 0.1 (or Remesh parameters with: Octree Depth=2) (Just to be sure that many faces get eliminated)
5. Click "Apply" on the modifier
6. Now Tab into Edit mode again and Blender should crash immediately.

I think Blender tries to restore the previous selection of the faces but fails.