Bad Frames from TDeint or AVISynth?

Please post a full-sized screenshot of the "corruption".

A sample corrupted frame 

Here is a .jpg of the captured .bmp of one of theworst examples. Other corrupted frames are mostly less severe. This one was of a still image contained in the video.

I never saw anything like that. Add the filters one at a time and serve into VirtualDub to view. Find out which filter causes the problem and report back here.

OK, I'll run some tests as you recommend. It will likely take a day or two as I'm quite busy with other things and since only the occasional frame gets corrupted I'll probably need to let things run a bit. By the way, another corrupted frame, also from a still, is even weirder, and completely different: the top 3/4 is normal, and the bottom 1/4, where there should be just a dark background, has large variegated coloured patches - looks lile someone's idea of digital art.

Some time ago, I had these errors, too. I don't know exactly, what caused them to disappear. Check/change the following: 1) HuffYUV - Version 2) IDE-Controller Drivers 3) IDE Cables 4) System memory 5) Clock rates and timing settings

Another quick thought, if you use P4, disable hyperthreading, which in my experience has caused some scattered problems in Avisynth/video editing.

Thanks 

sort of OT, but if it's just a videoed lecture going to DVD, then there's no reason to deinterlace. just make sure your field-order is correct and encode interlaced - TMPG should be able to handle it pretty well, so long as your bitrate isn't impossibly low (where it'd probably fail on progressive as well). talking heads are the easiest thing in the world for mpeg-2, interlaced or not.

Tis true