Thanks for that!
I ran the memory test and it didn't find any errors, so I thought this had turned up a blank.
But ever since I ran the memory test, not only has that WinLogon crash disappeared, but a whole host of other instabilities on my computer appear to have cleared up!
I have no idea what that memroy test did, but it appears to have blown away some dust on some component somewhere, and my computer is back to its old, functional self!
THANK YOU SO MUCH!