--- Operating System ---
Windows 7 64bit

--- Blender version with error ---

Blender 2.67-2.67b 64bit (official build).

--- Short description of error ---

Derived mesh explodes to infinity while using solidify modifier with tubular non-manifold base mesh if "Even Thickness" AND "High Quality Normals" are checked (but not both). This is probably related to the geometry of the base mesh. However I could not find any similar cases where non-manifold mesh would explode.

See attached file for this particular geometry.

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

1. Open attached file
2. Go to solidify modifier ("Circle" object).
3. Notice that "Even Thickness" is set and mesh looks as expected
3. Check "High Quality Normals" option -> mesh explodes
4. Uncheck "Even Thickness" -> mesh looks good
5. Check "Even Thickness" again -> mesh explodes

Kristijonas