Congrats on the SNES and NES! Coincidentally, after much searching, I managed to find TWO MINT condition NES systems on ebay, they were in practically unopened condition, came with mint condition box, with all manuals, wrappings and the "new" smell still very much present; still have my original SNES (and Contra III btw) so I will hold off on picking up a new-ish SNES. Anyway, the NES, especially, had lots of weird graphics that would sometimes be rendered in the typical "overscan area" of a CRT, perhaps that is part of your problem; though the SNES usually never had any wierd, out of overscan range issues, so perhaps not). Other than that, perhaps it is some sort of sync problem or even an impedence mismatch. If there is an impedence switch on the monitor make sure it is switched to 75 ohms. Last thing, although this is blantantly obvious, try different cables if you have them. I hope this works out for you, though I have a feeling it may be something with the scalar not liking the NES scan pattern (it is a little odd, even on CRT's it does not look perfect, hence why you usually see the wierd off-screen graphics on TV's that have appropriately reduced overscan).