If you know about their existence, is easy to find those lines: either use rubber-band selection or select any other object and hit the tab key to cycle trough all objects.
The first I konw of them is when I try to print the drawings! Even then I may not spot them immediately. The drawings are very detailed (the simplest ones have over 200 objects). Cycling though them would be, to say the least, tedious. It is extremely rare for me to want line thickness to be less than 0.2mm so a utility or routine that could snag out everything less than say 0.05mm and with no fill would completely solve the problem for me.
The rubberbanding method aught to work for you though. Zoom out and make a huge select box over most of the screen. If the selected area is larger than your drawing area, you'll be able to find the line.
-- Michael Moore ------------------------------- www.stuporglue.com