Problems with Lightmapping and realtime lights

Hi. I'm using the latest version of Unity and have just started lightmapping my levels with Beast (previously was doing this externally in Blender).

The results are good, but throwing a couple of problems:

My level environments are all single objects which use the vertex lit shader and I have a single realtime point light in my scene, which I use to cast a red glow on the level geometry where a laser hits. This is a vertex light, not pixel.

Unfortunately, after I lightmap my level the vertex light no longer affects the geometry - unless I set it to pixel, which is terribly slow and not needed for this effect. I also have to change the material on my object to diffuse instead of vertex lit to get the light to show up.

Why does lightmapping an object break its realtime lighting?

If I want my object vertex lit and reacting to a vertex light why would lightmapping it break this, and require a point light and a different shader (diffuse)?

Any help would be greatly appreciated.