I'm using Premiere 6.0, capturing via FireWire and using the
compressor "Microsoft DV (PAL)". This problem occurs when I add a title in the superimpose track, for instance subtitles. I get a kind of fixed pattern noise, which looks like vertical dotted stripes that are completely fixed. They appear when the title is there, and disappear when the title isn't there. By zooming in, it becomes clear that it's not stripes, but a grid of dots that are exactly 8 pixels apart horizontally and vertically. The pixels aren't all the same color - every 8th pixel has somehow been darkened (or maybe the problem is that they retain the same color, while other pixels shift all the time, I don't know).

If I export a still (bmp) from the project where I added the title, the image does not have the dots (although the title text is there of course). But if I export a clip with the title, the dots are there on the exported clip. So if I import this clip again, and then export a still, the dots are there on the image.

LOOK HERE: http://home.powertech.no/npk/DVL-temp.htm
(The two top images are full bmp-images so they're pretty big. The two bottom images are small.)

Some other things, like adding effects, exporting, and then adding effects again, will sometimes also produce the same dots.
It doesn't look good, it looks like some sort of "fishnet" filter (similar to an aged film filter) has been used. It's much more apparent when the film is moving, than on a still, because the dots are completely fixed.

Some things I've read on the web make me think that this is maybe some sort of DV artifact. (But I haven't been able to find anything describing this exact problem.) Titles demand a very exact contour, and this eats up the "bit budget" of the DV codec. Still doesn't explain why this exact problem occurs; the result should just be less definition or more blocking artifacts, right? That would be preferable.

Any insight is greatly appreciated!

I haven't described the problem correctly. Please ignore this for now. Sorry.