New users can not login

Joomla 2.5.19
CB 1.9.1
PHP 5.4.29

I just noticed that new users are not able to login, they get "Incorrect username or password. Please try again."

Here is what I know by looking into the database. For all non-working users, the password begins with $P$D. If I manual change the password (in database field) with the MD5 equivalent and I am able to login.

Also, if I login into an existing user and change their password, the password is changed to begin with $P$D and unable to login.

Thanks for the help.

Update --

I tried this situation on another site (different hosting server) and everything worked.

I seem to think this problem occurs on 1&1 (host site). Has anyone else experience this problem on 1&1?

Any work arounds because they are not helpful at all.

Thanks

yes, this host is probably not compatible with Joomlas encryption methods.. 1&1 is one of the worst Joomla hosts out there

Update

I was able to install a new Joomla 2.5.22 site on the same 1&1 server. Verified that creating a new user and changing the password in the User Profile still allowed the user to login in without CB.

Installed CB 1.9.1 and verified the same thing - all worked.

Matched problem site's modules and plugins with new working site. User can login as long as the password is not changed to the $P$D prefix. Sometimes login doesn't change the password and sometimes it does. If the password is changed in User Profile, the user can't login because of "Incorrect username or password." - the password is $P$D format.

I have reinstalled CB 1.9.1 and nothing helped.

I think the only difference between the two sites, is that I have created registration fields that are not on the working site. I'm afraid to change these on the problem site and lose the info.

Because I'm able to get this to work on 1&1, it is not a server issue. It seems to reside in the changing of the password from User Profile.

Is there a way to do a fresh install of 2.5.22 and CB without losing the registration page, users, and content?

Any idea?

UniMult wrote: Because I'm able to get this to work on 1&1, it is not a server issue. It seems to reside in the changing of the password from User Profile.

Agree.

What extra extensions/CB add-ons have you on the production site that you do not have on the test site?

I have removed the following modules:

CB Online
CB Workflows
CB Subs

The enabled plugins are the same between the two sites.

I have removed the following CB plugins:

CB Paid Subscriptions - GB (cannot unpublish)
CB Confirm Email
CB Paid Subscriptions
CBSubs Folder Access
CBSubs Plan Image
CBSubs additional plugins

The working and non-working site are as close as I can get them in what is loaded or installed. The biggest difference is I have a language package that I don't want to uninstall (but is unpublished) and I have a custom CB registration page. I don't know if I can removed this without losing my existing user info.

Further testing shows that even new users are not able to log in because when password is in $P$D format. Changing it back to old format allows the user to log in.