Why would my wallet, which has been OPEN and mining PoS for some time now, suddenly be Out of Synch with the network?
It has been like this for several (more than 6) hours and it doesn't seem to be catching up.
This has happened on two wallets on different machines?
Very confusing

There was an mandatory upgrade that was needed in order to stop the checkpoint to old warning and also to provide more stability to the coin. Not every one upgraded in time so the coin forked.
You may be one of the ones that are on the non-official fork.
Please follow the steps listed here to get back on the correct fork.
https://bitcointalk.org/index.php?topic=683450.msg7966986#msg7966986