The file /usr/X11R6/lib/modules/extensions/vnc.so should be compiled with "-ljpeg", but it is not. This causes clients requesting JPEG compression to crash the server. It looks as though someone tried, as "EXTRA_LIBRARIES = -ljpeg" did make it into xc/programs/Xserver/vnc/module/Makefile, but it is not effective.
*** Bug 50953 has been marked as a duplicate of this bug. ***
This was RealVNC Beta 4, which is no longer in portage emerge tightvnc-1.3_alpha5 for a newer faster tightvnc