I'm seeing mixed reports on proposed remedies for that issue in the stock Eris with the update. Multiple reboots works for some; just power down the device, wait for about 30 seconds, then power back up. Don't try to put it to sleep, power down again, then back up after a short wait.
Try the sleep function with the power button after repeating the power down/up several times.
Another one is to remove the battery with the device fully on ("live battery pull"). I don't recommend this (as I used to), just reporting that I've seen some posts claiming success with various issues by doing this.