There's a problem with the windows wallet version 1.6.6.7. It gets stuck at block 956987. I downloaded the bootstrap, this works fine. Wallet syncs up to block 956987 then further blocks get rolled back to 956987 with an error in the log saying:

04/10/19 06:50:16 ERROR: CheckProofOfStake() : INFO: read txPrev failed
04/10/19 06:50:16 WARNING: ProcessBlock(): check proof-of-stake failed for block

Eventually the chain starts downloading again, and this failure repeats over and over. I have a copy of the blockchain past this point on a separate machine. I've heard this has also happened to other POS coins, and the solution is to update the bootstrap file (which is currently quite old btw)

Thanks

EDIT: So I've downloaded 1.6.6.7b and the new bootstrap. Now it only makes it to block 820988 before the same problem occurs.