[Phoenix-D]

"What kind of data/ai error is likely to generate an Access Violation error?"

That depends on where you're getting the error. If during an AI turn, the AI files..probably a ship design (creating ships with more than 255 Standard Move used to do this; not sure if it does anymore).

If when warping into a new system, like below..huh. Only thing I can think of would be an invalid system type, but that should show up during galaxy generation, at the start of the game..