You are running a package without the requirements. Specifically the xotcl request monitor which requires a specific thread library that you do not have installed. Uninstall the xotcl request monitor.
Gustaf said pretty much the same thing "
ben, you have not only installed xowiki, but the xotcl request monitor as well. the request monitor requires libthread (see http://media.wu-wien.ac.at/download/README-xotcl-core). xowiki does not need the request monitor or libthread. so, you could either install libthread, or uninstall the xotcl request monitor.
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