Digital BW, The Print

I'm printing with an 1160 using MIS' VM inkset. I've recently noticed 
that my A3 prints have an evenly spaced (about one half inch between 
them) series of very very small (almost not noticeable without a 
loupe) dots running across the print. This series of dots continues 
across to the end of the paper -- in other words, right across what 
would otherwise be blank paper. Of course, I don't want this to be 
happening. Anyone have a possible diagnosis and cure? It would be 
muchy appreciated.

Chris Hargens