The latest builds of LXFree and LXBeams (leading up to v2.1) have a renamed library folder to comply with Apple guidelines. Because this change has been coming for a while, older versions recognize the new library location. But, from now on, the standard libraries will be stored inside the application rather than in the system Library directory. Again, this is due to Apple restrictions that may be enforced in the future.
Here's the rub. LXFree/LXBeams 2.0 versions recognize and prefer the new "com.claudeheintzdesign.lxseries" library folder. If it exists, they do not look for the old "lx" folder. (The new installer does not delete the old "lx" folder in case someone had stored custom files there even though they shouldn't have.) So, if you have mixed 2.0 and 2.1 versions installed, the 2.0 version will not find the standard library files.
If you need both 2.0 and 2.1 versions of LXFree and/or LXBeams installed at the same time, the solution is to move all the files and folders from inside the older "/Library/Application Support/lx" folder to the "/Library/Application Support/com.claudeheintzdesign.lxseries" folder. (Note that this is not the "/Users/<username>/Library/Application Support/com.claudeheintzdesign.lxseries" directory which holds your custom library files.)