Here's the history the terminology of PsF and P -
http://en.wikipedia.org/wiki/Progressive_segmented_frame. Saved me some time typing - Wikipedia never cases to amaze. So, that's not the source of your "interference".
I worked a lot for BBC and Channel 4 (England) as a HD Camera Operator. I shot 25p for them often obviously using a Sony f900 camera, because they're a PAL country obviously. If I played PAL on my NTSC HD monitor, using a F500 VTR set to 25p I'd get something that I'd also describe as "interference". Also, if the VTR isn't set to the right frame or field rate, I'd also get something I'd describe as "interference". I suspect, the issue is one of those two problems. Play it back on the F900 too in 25p, and if you can see it through the viewfinder playing property without the "interference" you can eliminate the source as the issue...and breathe a lot easier.
Good luck.
Best,
Kevin
http://www.saturnaliaproductions.com/
