I have had this error multiple times and although it does not stop robotstudio it does make random attached graphics stop moving with their attached parent. I did put this question on when I was using 6.07 when I was getting attached items not moving, but never had the exception. I have now gone to 6.08.01 and still having this problem
As you can see from the snapshot the gripper to the left has become left behind from the robot (underneath the error popup), which cases me an undocking error on a custom docking smartcomponent as it can no longer see the graphic on the robot docking sensors. I will be using attachments in the future for part flow (picking,dropping and welding parts together) and this error will stop that from working