Running Finder 6.0, System 4.2 on a Mac II, I found this catastrophic
Finder bug over the weekend:
If the icon mask (second half of the ICN# resource) for a file is
blank (all zeroes), attempting to drag the file in an icon view kills
the Finder. Sometimes it bombs, sometimes it scrambles the screen,
sometimes it just freezes solid - no mouse, no keyboard, no de*.
To fix the problem, use ResEdit to open the file which provides the
brain-damaged icon. Open the ICN# resources, open the offending ICN#,
and draw a mask. Close and save the file.
The defective ICN# is also in your desktop file, so you can either
(a) delete the desktop file while you're in ResEdit;
(b) edit the desktop copy of the ICN# in question in ResEdit; or
(c) hold the command and option keys while exiting ResEdit, so that
the Finder will offer to rebuild the desktop.
The program in which I found the problem is Mandelbrot Microscope, a
color Mandelbrot set plotter. Only the saved set icon has this
problem; the application icon and saved color table icons are OK.
Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142-1214