The Pismo keyboard has a friction plug, and sometimes it comes loose. Just take the keyboard out (check if the lock is open - the slot near the NumLock key should be in the horizontal position) by pressing the latches towards you and lifting (they are between the Esc and F1, and F8 and F9), then pressing the plug at the end of the flat cable back into its socket until you feel it is secure. Then close the keyboard...
If that doesn't help, send it for service. The E key rubs into the heat shield that protects the keyboard from the heat of the CPU, but it's *right over* the CPU: maybe you're causing a bad contact, but in that event, the Pismo should shutdown immediately instead of going to sleep.