video corruption

I have a model exported from Milkshape of my building.

When the player moves around I get a lot of random "glitches" on the screen. The models are clean as far as I can tell but these small imperfections are annoying. Has anyone seen this or similar ?

I am using a 2.8Ghz AMD with 1.5 Gb RAM and a Geforce 128Mb Graphics card.

I also get random slowdowns while moving around.

I am also using Blitz V 1.87.

Without code I can only make a couple guesses :

1) Your video card drivers might be causing the problem

2) Your scale of the Blitz unit may be a lil' too large, which can cause Z-Ordering problems.

Unwelded vertices also springs to mind.

or have a true framerate that is near 60Hz, so sometimes it misses the vsync and shows a few frames with 30Hz, then 60 again. Looks pretty unpersistent. Compare it with Flip false.

Thanks, I will check all of these