I too got the same error for a IIsi:
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I installed the X libraries as per the README Files.
When I type startx I get this message:

ld.so: xint: libXmu.so.6.0: No such file or directory

I know that libXmu.so.6.0 in in the /usr/X11R6/lib/ directory but I don't
know what is causing this error.

I tried typing in X and then it brought up my X window but I could not do
anything. I tried control+option+left arrow,  control+option+right arrow, but
no menu came up for me to open an xterm....

Thanks for any help you can offer 
-Steve More