In slackware 1.1.2 /lib/cpp is set up as a link:
/lib/cpp -> /usr/lib/gcc-lib/i486-linux/*.*.*/cpp
which of course is wrong. It can be cured by:
ln -sf /usr/lib/gcc-lib/i486-linux/2.5.8/cpp /lib/cpp
(substitute your version of gcc for 2.5.8 if yours is different).
The symptoms of this error are that X programs can't read their resource
files, because resource files are processed by /lib/cpp. In particular,
'xdm' can't read /usr/lib/X11/xdm/Xresources.
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