System Information
Windows 7 64, HD 5770

Blender Version
Broken: 9337574 (2.71 release) + f0f398d

Short description of error
Blender Render:
Viewport shading in texture mode has problems with Autosmooth:

• if minimum 2 materials are assigned on the mesh
• if they differ in their transparency checkbox setting (enabled or not)
• if Properties>Object>Display>Transparency is checked.

(All three must be true at the same time)

This seems only visible in Objectmode, Editmode and Render arent affected.

Exact steps for others to reproduce the error

• Add a Lamp (Point).
• Add a Cube.
  • Go to Properties>Object Data>Normals>enable Autosmooth.
  • Go to Properties>Object>Display>enable Transparency.
  • Give Cube 2 materials (different color).
    • Assign them both on the mesh.
    • Enable Transparency for only one material.
• Set Viewport to Blender Render & Textured Mode.

Problem: Wrong shading and shadows in Objectmode.

Note that if you assign only transparent materials, or only non-transparent materials on the mesh, the problems disappear.