"White" Stripes on Captured Images

[NuPogodi]

Hi, folks!

When capturing (iuVCR) analog TV programs (cable), i can sometimes see the frames with broad stripes of slightly reduced intencity (see image http://img89.imageshack.us/my.php?image=stripesxw0.png , right bottom). These stripes are especially visible at dark areas. They occur for several seconds and may slowly move through the whole frame. It looks like low frequency interefence effects. Does anyone have a suggestion
i) why it happens
ii) how to solve a problem
iii) if it cannot be solved by hardware methods, is there any filter (say, AviSynth) to remove these stripes after the capturing process?
Thanks.
http://img89.imageshack.us/content.php?page=done&l=img89/7193/stripesxw0.png

[FlimsyFeet]

Do you get any humming in the audio as well?
May be caused by a "ground loop".
Look here: http://forum.doom9.org/showthread.php?t=81040

[NuPogodi]

I've noticed no problems with audio (maybe, i should hear it once more). And I'm afraid, the "ground-loop" is scarcely possible. Why? I capture with laptop, its power supply is not grounded at all (the power supply cable has only 2 wires, both are "phases", not "ground"). So the only "ground"-point is the TV-cable. I've already tried to connect / disconnect the TV-"ground" to the ground in the 220ACV socket - no principal difference was observed.

[LoRd_MuldeR]

Damn, I got White Stripes on my capture too :eek:

http://img45.imageshack.us/img45/861/whitestripeslx2.jpg