Vertex Texture Lookup Breaking in Unity 3.5

First, some background information: 1. My project contains a plugin which streams textures into Unity. 2. A custom vertex shader uses tex2Dlod() to retrieve this texture and manipulate the alpha channel. 3. The alpha channel is then used to displace the vertex.

This process worked as desired in Unity 3.4, but now causes crashes in Unity 3.5. I know it is atypical to access textures from outside the render thread, but it worked in 3.4. Does anyone have any hints as to why it breaks in this latest release?

Note: The shader works in 3.5 with a static texture, but not with streaming.

Note: Out of curiosity I built a surface shader to carry out the same function, and tex2Dlod did NOT cause a crash. Why would the surface shader work and the vertex shader crash?