I've searched - I really have - but I can't find an article that explains the error code I've got on my data

"VAT ledger record index has invalid ID"

I recently set up on a new computer, had hell trying to reconnect to the remote data and so had to restore from a back up file on the new PC in order to get the VAT return done in time.  I'm wondering if it thinks I'm using a duplicate VAT number because I haven't reconnected to the remote data yet, because I just can't face that yet. 

So my question is what exactly does the error code mean and what do I have to do to fix it?