I've already installed X11 and Crossover says it's not there!

Sometimes the installation of X11 doesn't create the proper symlinks, and even though X11 is installed on your Mac, Crossover can't see it. To check and see if this your problem, open up a terminal (Applications>Utilities>Terminal), and run the following commands (i.e. type/paste in the command and press "enter")

ls -l /usr/lib/libXplugin*

and

file /usr/lib/libXplugin*

The following is an example of what you should see on a system with X11 properly installed:

jack-mac:~ jack$ ls -l /usr/lib/libXplugin* lrwxr-xr-x 1 root wheel 18 May 18 15:08 /usr/lib/libXplugin.1.0.dylib -> libXplugin.1.dylib -rwxr-xr-x 1 root wheel 263408 Feb 11 2010 /usr/lib/libXplugin.1.dylib lrwxr-xr-x 1 root wheel 18 May 18 15:08 /usr/lib/libXplugin.dylib -> libXplugin.1.dylib jack-mac:~ jack$ file /usr/lib/libXplugin* /usr/lib/libXplugin.1.0.dylib: Mach-O universal binary with 3 architectures /usr/lib/libXplugin.1.0.dylib (for architecture x86_64): Mach-O 64-bit dynamically linked shared library x86_64 /usr/lib/libXplugin.1.0.dylib (for architecture i386): Mach-O dynamically linked shared library i386 /usr/lib/libXplugin.1.0.dylib (for architecture ppc7400): Mach-O dynamically linked shared library ppc /usr/lib/libXplugin.1.dylib: Mach-O universal binary with 3 architectures /usr/lib/libXplugin.1.dylib (for architecture x86_64): Mach-O 64-bit dynamically linked shared library x86_64 /usr/lib/libXplugin.1.dylib (for architecture i386): Mach-O dynamically linked shared library i386 /usr/lib/libXplugin.1.dylib (for architecture ppc7400): Mach-O dynamically linked shared library ppc /usr/lib/libXplugin.dylib: Mach-O universal binary with 3 architectures /usr/lib/libXplugin.dylib (for architecture x86_64): Mach-O 64-bit dynamically linked shared library x86_64 /usr/lib/libXplugin.dylib (for architecture i386): Mach-O dynamically linked shared library i386 /usr/lib/libXplugin.dylib (for architecture ppc7400): Mach-O dynamically linked shared library ppc

However, if your installation of X11 missed the proper libraries, you'll only see

jack-mac:~ jack$ ls -l /usr/lib/libXplugin* -rwxr-xr-x 1 root wheel 263408 Feb 11 2010 /usr/lib/libXplugin.1.dylib jack-mac:~ jack$ file /usr/lib/libXplugin* /usr/lib/libXplugin.1.dylib: Mach-O universal binary with 3 architectures /usr/lib/libXplugin.1.dylib (for architecture x86_64): Mach-O 64-bit dynamically linked shared library x86_64 /usr/lib/libXplugin.1.dylib (for architecture i386): Mach-O dynamically linked shared library i386 /usr/lib/libXplugin.1.dylib (for architecture ppc7400): Mach-O dynamically linked shared library ppc

To correct this problem, simply run the following commands in terminal:

(Note: you'll want to copy the commands that come *after* the "$". Don't copy the "$" itself.)

$ cd /usr/lib

$ sudo ln -s libXplugin.1.dylib libXplugin.dylib
you'll be asked for your admin password after this one

$ sudo ln -s libXplugin.1.dylib libXplugin.1.0.dylib

And this should fix the problem.