Hi George!
Thanks for the offer, but I ended up solving the problem. (Well, to be more precise, Haden Hale of Pangolin solved my problem!) I was in Florida this past weekend, and I dropped by the Pangolin office on Saturday to meet with Hayden. He was still pretty jet-lagged from his trip to China (he got back late Thursday), but he still agreed to meet with me.
Turns out that a common problem with the Quad Mod 32 board is that the pull-up resistors for the data bus get shoved around, and sometimes their leads touch. (These are the vertically-mounted resistors that sit near the long edge of the card, away from the ISA connector, about mid-way along it's length.) Sure enough, two of them were touching on my board. Hayden moved them apart a bit, and I suggested installing some shrink-wrap to prevent it from happening again. We did just that, and then stuck the board back in the docking station.
Tada! Just like that, it started working. We loaded up showtime, and everything worked fine. I loaded up one of the shows that came on the disc and played it in the preview window. Then we played around with Lasershow Designer a bit (including the abstract generator), before shutting it down.
So a big thanks to Hayden for agreeing to meet with me and have a look at the board. (Glad it was something simple!) And thanks to you, too, George, for your offer to help. I need to call you one of these evenings anyway and catch up on things. (But I've been busy as hell myself!)
Adam