Try resetting your account details and see if that helps. If that doesn't work, check if it's only Minetown that doesn't allow you to connect. If all else fails, if you're on Android (I believe it's only on Android, they may have an iOS version as well) I'd give the app "Pickaxe Chat" a go, it's a smoother alternative to Minechat.

It's a bit of a downgrade from the previous theme in my opinion, it's a very nice design but it just isn't as good as the previous one. Just my thoughts though, it looks alright so far ^^