Hi Julian,

It's the scanner. BTDT. You're probably fouling a sensor somehow. AFAIK film wouldn't show straight lines if it were a chemical problem unless you dragged it through a pair of contaminated squeegee tongs or other nasty contraption. Scanning is OT here, the good folk at http://www.dpug.org/forums/home.php will be more knowledgeable about these things. :-)