this seems to be caused by a problem in the Laubwerk Catalog files. We fixed the file for the upcoming 1.0.8 update but 1.0.7 still has it. If you don't want to wait for the update, you can use the attached file to fix it yourself. Open the Laubwerk Forest Pack catalog location in the explorer. When you sticked with the default installation path, it will be at: C:\Program Files\Laubwerk\Plants for Forest Pack. In there are folders for each installed plant species. Inside each species folder is a laubwerk.ms file that you can replace with the one attached to this message. That should fix your problem.
EDIT: Since this is only needed for the initial import into Forest Pack, this process only needs to be done on the workstation, not on any machine that's a pure render client.
Sorry for the inconvenience!