SOLUTION FOUND!!:
ok I had this issue and searched all over creation and no one gave me a straight answer, so I figured it out on my own.
the problem is that 3.1 uses PHP 5.1 or higher, if your server doesn’t support that then your blog won’t work you won’t be able to log in and you’ll be redirected.
the solution is to talk to your service provider and ask them to switch you over to a newer server that runs PHP 5.1 or higher.
I use IXwebhosting and it seems that everyone that is having this issue uses them. I have been a customer of theirs for almost 5 years now, so my server was pretty old. it was free to switch BUT I had to re-upload everything and rebuild my databases and email and everything, basically I got a new blank webserver. but it was free.
and my old stuff is still there for 2 weeks after I told them to switch the servers (it took me a week to backup 5+ sites and databases).
the cool part about the switch is that the new PHPMyAdmin has a synchronize feature! so I just pointed it to my old server and it imported all my old databases instantly! it’s like the change never even happened!
so there you go, a long post that actually HELPS!
-Lumpy
PS, please don’t ask me for help in doing this, I know how to help but honestly I don’t have the time, I work 2 jobs at 12+ hours a day, plus a family. sorry ??
PPS- you can find the older versions at:
https://www.ads-software.com/download/release-archive/
hope that helps.