Pater pierre

I'm running a V570 with expansion modules : Ex-A1 with 5x IO-DI8-TO8 and 1x IO-AI4-AO2; I recently added 2x IO-D16A3-TO16. Now the PLC gives very frequently an expansion error. When this occurs, PLC gives the black text screen, the 2 new modules get a flashing green run led, the older modules remain running (fixed green led). Never had problems before unless with these new modules. I even disconected all IOs from the new modules, but it keeps going from time to time into expansion error. Are there incompatibilities known with this configuration? Is there a way to manipulate the conditions that cause the error (change SB's, timers,...?) Suggestions welcome !