Hi Alauriana
Unfortunately in this case you dont have any chance, except recompiling the flotsam groups module of opensim and/or your viewer.
This is not a bug in jOpenSim, but a sort of incompatible communication between the Flotsam module of OpenSim and the viewers.
I once (ages ago) managed to fix that in my grid, but of course will get overwritten at every update again.
Let me see if I can fix it once again for OpenSim 0.9.0.0 and post it here, but can not make any promise
Greetz
FoTo50