It’s certainly not my intention to waste your time, and I was not aware that this is the third installation you have created for troubleshooting purposes.
In any case it seems that with just our plugins and nothing else running – on an otherwise clean WordPress installation – you are still hitting upon difficulties. That could be due to some environmental issue relating to your hosting package or some other factor I’m unaware of – realistically though, I’m sorry to say, we’ve reached the end of how far we can help you troubleshoot this one.
That’s bound to be disappointing for you and is for us, too, but I’m afraid there isn’t much else we can do here.