thin line across graphic

[MVMusic]

I'm trying to save a big graphic in Xara P&GD 2013 (version 8) and I keep getting a line across the whole picture. If I save it at about 6000 pixels wide, I can see the line, at 2000 pixels, I don't. There are no objects that could have a line at that specific area and there are no line weights at all. It's a JPG, but I tried PNG and the line is still there.
Maybe somebody has any idea of what could cause it...