User login weirdness after host change

[Meestor_X]

So, we moved hosts, but the url is the same.
Was running 4.2.3 on the old host, downloaded 4.2.5 from vBulletin and uploaded it to the new host. Same folder layout as the old host, same domain name.
Updated config.php with database settings
Ran the update on the database.
Deleted /install
As administrator, I can log into the admincp and the forum.
If I type in a "bogus" username and password, I get no error page or login page, it just refreshes the page to the non logged-in forum home page.

I checked cookies settings in admincp, tried many suggestions I saw on the web, like clearing cookies in the browser, turning on non-cached headers (I think), disabled plugins, etc. So far nothing seems to fix it.

You can see it yourself by going to the forum and trying a login with a bogus name and password. http://www.mindplacesupport.com/forum

Thank you for any and all help - Can't seem to figure this one out!