Please download and hotfix_20110725 and install it.
The hotfix can be applied while sessions are running. Once the session server log shows the DPA has applied both DPA-3-1-6 and DPA-3-1-7, it should be set to inactive and once all the sessions on the DPA have completed it should be rebooted to clear any orphaned processes from earlier sessions. Then that DPA can be set back to active and the same process can be applied to the second DPA**