PHP downgrade, error message

[LLIFE]

Any ideas?

I downgraded to PHP 4x from 5x, I get the following error:

There seems to have been a problem with the database.
Please try again by clicking the Refresh button in your web browser.

An E-Mail has been dispatched to our Technical Staff, whom you can also contact if the problem persists.

We apologise for any inconvenience.

Then I get this in the email:

Database error in vBulletin :

mysql_connect(): Client does not support authentication protocol requested by server; consider upgrading MySQL client C:\Inetpub\plan.0\lowriderlife.com\forum\includes\class_core.php on line 273

MySQL Error :
Error Number :
Date : Tuesday, January 3rd 2006 @ 09:06:21 AM
Script : http://www.site.com:8080/forum/admincp/index.php
Referrer :
IP Address : 160.81.201.126
Username :
Classname : vb_database

[Chuck S]

That would be a vbulletin error message but it would appear to me you did not install PHP with mysql support.