On advice from the good folks at Computer Concepts (Bothell WA), disabled the NVIDIA graphics driver and ran the PC using the native VGA driver. Display was somewhat distorted, but MC didn't crash the PC and did complete the print. However, the MC window turned black except for the title bar, and the app was unusable (for checking temps, progress, etc.) otherwise.
My eventual fix was to switch to another Windows PC, this one without an NVIDIA graphics card, and MC works OK. Thanks to the bare-minimum Intel HD driver, graphics are on the jaggy side. Slow refresh of the MC window is an issue after the print starts. But - just finished a couple of 6-hour prints without issues. YMMV.