'97 IP going crazy

Trying to debug an electrical gremlin on a '97 Buick Century. The IP has gone crazy... tach and speedo work, gas is stuck at 1/2, coolant at full-out hot, oil-pressure light rotates between blinking and solid, and the info-center has some parts of the letters solid-on, and the rest are doing random dances.

Any ideas? De-energize the entire car, by pulling the battery? Pull a specific fuse? Bad IP? Bad ECU?

Thanks!