I supose you are using LC 2.0.0 beta. If this is rigth then:
Ubutu & debian: update to daily buids
linux, RPM based, update to beta5
http://librecad.org/cms/home/installation/rpm-packages.htmlwindows: update to this:
http://forum.librecad.org/LibreCAD-installer-2-0-0beta-5-git-from-2013-05-10-tp5708069.html