Constant Crashing Causes Consternation

My problem has only cropped up recently. It doesn't crash on loading the game. It doesn't crash on loading a career. It only crashes in the middle of a convoy battle. it doesn't matter if I have extra smoke effects loaded or not; it doesn't matter if I'm looking at the ship I just sunk or I'm at 50 meters reloading torpedoes. I can play for hours just sailing around, or I can load a game I saved just before going into action. It doesn't matter. Somewhere in the middle of the battle it crashes, and I get the Windows Error Report.

I'm assuming it has something to do with my RAM. I supposedly have the required 512, but I don't have the recommended 1GIG. When I install the game (and I've reinstalled several times) the screen tells me that all my requirements are met except for memory. I didn't have this happen previously; it's only started in the past few weeks.

Any ideas?