Hi B0b
not au-fait with VM TBH
but basics are still the same
have you gone through the re-install, as though you were starting afresh?
as it has run for a year, I would look to something failing / corrupting

or
have you done a re-start on th eserer itself
now I know that isn't what we like to do, but sometimes ..........

as chkdsk only examins disc for bad sectors, it isn't looking at quality of data stored theron

luck to you