Why do my Mat Ed slots show up black?

[Renderhaus]

My Material Editor slots in 3dsMax2008 occasionally show up black (after taking anywhere from 5 to 30 minutes to load) from within pre-existing scenes - never from the start of a brand new scene.

1. My V-Ray license server IS active prior to even launching 3dsMax2008. (as I already know that this is the first recommended "fix")
   
2. The V-Ray license is local to my machine (laptop) and not at all networked.
   
3. The dongle IS completely and properly seated in the USB port.
   
4. I have no non-Vray materials either in my scene, nor occupying any Mat Ed slot.
   
5. This seemingly random phenominon did not begin occuring until after I installed 1.5sp3
   
6. It is not resultant from missing material maps - all maps are local and no links are broken.

I am about to pull my friggin hair out over this, because I cannot seam to pinpoint the problem. It does'nt happen with every model I create. It never happens on a newly created max scene. It doesn't happen all the time - but once it does happen, it continues to happen for that specific file. It is now occuring each and every time I open any tree from the Archmodels vol.58 collection.

And to further frustrate things, the only solution I seem to find when searching this topic out is "Activate your licence server". But my license server IS active and I'm still getting this strange anomoly.

Can anyone help me? Please advise.

[Renderhaus]

Nevermind.

I figured out the problem. I was using the Direct3D display driver. Once I switched back to OpenGL the problem dissappeared completely.