You likely have a long orphan, i.e. a block deep into the chain is missing, triggering 100k+ block reorgs over and over. I don't know how these happen, but I've ran into them myself recently however.

This isn't an Armory issue per se, your copy of the chain is corrupted somehow. You will need to reindex Core first to fix the issue, Armory cannot help you here.

Call bitcoind/bitcoin-qt with -reindex and let it do its thing. Once it succeeds, you can wipe Armory's database folder and try again.