Flashing gear indicator on 89

Arg! It's at it again, doing a bunch of weird stuff that no one has an answer to! {slams head against wall}

I have an '89 regal limited with the option dash module... all digital. About a week ago, I was driving around as usual, and suddenly, the gear indicator started to flash. Normally, it shows P R N D 2 1 [Automatic Overdrive], with a square around the gear its in, and the AO lights up if AO is on. Now, there's a flashing square around every single gear. So I shifted down out of AO, and everything SEEMS normal-- there's just a square around D, and the AO light is off. Seems normal, until I try to shift gears again. Now the gear indicator doesn't go anywhere. It's frozed on D (no AO). I shift down to 1, then back up, no dice. Neutral then back down. Nope. Park. Nope. Turn off the car, nope.

And now it's even weirder. If I am in ANY gear except D (no AO), it flashes (squares around everything). And when I first start the car, until I've driven a minute or two, even D (no AO) will sometimes flash.

I've checked all the fuses, and they all look fine. (Except for the Primary Cooling Fan 30 fuse, which had blown again, which I replaced, which didn't change anything). The only thing I can think of is an alternator? The original one died a few months back, and the replacement died right after, and ITS replacement always seemed to be a volt or two short of how the car used to "feel". (I'm not a mechanic, but I know when the car doesn't feel right, y'know?)

Does anyone know what the flashing means? The manual doesn't mention it, and I haven't been able to Google anything useful. Is something actually wrong with the car, or is just being a fidgitly little jerk again? (The bizzare issues I've had with this beast over the past six years would fill a book...)

Thanks in advance for any advice!