The remote host is missing an update as announced via advisory SSA:2007-110-01.
A new x11-6.9.0-i486-14_slack11.0.tgz patch is available for Slackware 11.0 to fix the inadvertent inclusion of two old fontconfig binaries. Installing the original fontconfig patch followed by the original x11 patch would cause fc-cache and fc-list to be overwritten by old versions, breaking fontconfig. To fix the issue, reinstall the fontconfig patch. The x11 package has been updated so that installation will not be order-specific for anyone fetching the patches now. Sorry for the inconvenience.