Problem with NES, SNES, N64 on 20F410T TV...

[Eldergod]

Okay I tried to search the forums first to no avail so here it goes...
I have a RCA 20F410T 20" TruFlat TV.
Now the problem is that the video hiccups every five seconds or so with the nes, snes, and n64. No other systems have this problem.
Now it wouldn't really be an issue but th tv turns gray when the video hiccups and says invalid signal. It makes the games unplayable.
Does anyone have any suggestions of why this happens. I read somewhere that it may be due to the refresh rates or something...
Any ideas on how to fix this problem?

[Gamereviewgod]

Are they all connected through the same port through a switchbox?

How are they connected? Composite? s-video?

Does this happen with anything else you play on the TV, even if it's not as frequently or a game console?

[Eldergod]

I've used both the rf connection and the composite cables.
They are all connected individually.
Ive tried all three inputs on my tv and they are all the same...
Damn I just called my brother (we both got the same tvs for christmas back in the day...) and his systems do the same thing...
Would a switchbox help?
I have one...
Lemme go try it...