I have finally been able to sync the client on another computer, and the problem appears to be exactly what I described earlier in this thread: because KGW went into immediate effect rather than being scheduled for the future, everyone has created their own hard fork at the point they upgraded. It looks like krugercoin.miners-pool.eu were using the old client (and therefore old difficulty retarget algorithm) well past block 1120000, which is why their client is disagreeing with everyone who is trying to sync from before that point.

New clients trying to sync calculate retarget using KGW from block 1120000 and onwards, but krugercoin.miners-pool.eu has already calculated that block and added it to their chain using the old algo. So the local client will say hang on, the difficulty retarget that krugercoin.miners-pool.eu is suggesting is not the same as mine; disconnect for misbehaving.

I'm pretty sure this is going to have dire consequences for the network, because it means that anyone with their client below block 1120000 - either one that hasn't been started for at least a few days, or one that is syncing from scratch - will never get past block 1119999.

Let me repeat that again. New clients that are at block 1119999 or lower will never be able to proceed onto the correct chain.