I get this crash on my dedicated server (1.7.2, bukkit/forge compatible) whenever I try to place any frames in the world. I don't know if you're aware of it or if it's some other mod causing the issue but you may want to take a look. Using version 2.0.1 of RIM.
Crash report: http://pastebin.com/syFysjPC
Thanks for continuing to update this mod, keep up the good work!