Ferrite cores for Comcast cable interference?

Hi:

I have a 50" plasma monitor hooked to a HK A/V receiver by a 30 ft monster component cable. I have a VOOM box and a dvd player both connected to the A/V receiver by monster component cables and optical cables. I also have an old VCR connected to the receiver by a cheap set of composite cables. Everything is stacked vertically and I have no artifacts on the screen or sound from the speakers when the voom box or dvd player are off.


Last night, my voom started acting up so I connected my old comcast cable line to the old VCR so I could get the football game. The cable line was laying over all of my other cables and caused colored bands on the monitor (with the receiver off) and an a hum through the speakers and colored bands on the monitor with the receiver on (no matter what input).


Two questions:


1. Is this normal? I paid a buttload for that 30 ft monster component cable and I thought it was sheilded.


2. I have these ferrite sheilds that came with the display - where can I put them to solve this problem?


Thanks,

Joseph