Sorry for the anonymous post.
Under Mac OS X 10.3.x (Panther), CotVNC is able to connect to an
OSXVNC server with no problems.
Under Mac OS X 10.4 pre-release (Tiger), CotVNC is able to
connect to the same server, but now the screen looks like it's been
bleached by the sun for the year. All colors appear as white,
except for black, which looks like a very light grey. Of course this
makes it very difficult to actually use. Oddly enough, switching to
full screen mode causes the colors to appear correctly very briefly,
but then the next screen update will once again appear as white.