Last throw of the dice, because your box is clearly unwell!
Under the reset menu (Home > Help & Settings > Restart) there's an option for "Reset box and clear all planned recordings". This will reset the box, wipe your manual recordings and the EPG, but keep your series links intact - and then use the SLs and an EPG rebuild to start from scratch, as it were.
If that fails, you may just need to bite the bullet and call VM to (probably) have your box pronounced terminal.
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