Trouble with ofb stage

[gethane]

I've been using the ofb stage without incident for months. In my newest house, however, I'm seeing some odd things.

1) when I build a stage in a couple places in this house, its turning the wall black.

2) when trying to fix this (by taking walls out, stages out, etc) now when I build a stage, the top of it is turning blue, the kind of blue you get when missing a mesh or something.

any ideas?

i am using an nvidia 6600 gt, so I'm using really old drivers from june 2005 so that I don't have the bluescreen/hourglass problem.

ETA:  I have uni, nl and ofb but do NOT have FFS or glamour.