Okay, as per
Jag's House page, opening and closing the system folder a couple of times re-blesses it. Not sure if this works for early than 7.6, but I'm glad to know the trick.
Next challenge ... after upgrading to 7.6.1, the option to have resolutions higher than 640x480 has disappeared from the Monitors control panel Options screen. It was there before. And I did notice that about every other boot, it would go back to 640x480 with other options missing, but then a reboot would fix it.
My 475 has 2x512k VRAM chips in it so should be able to 1024x768 and one greater resolution.