I had the same exact problem and spent hours troubleshooting it. The only way I could get into phpmyadmin was to copy the php folder from my old easyphp 5.3.0 installation (which worked great) to the 5.3.1 installation.
Apparently there is an issue with php that causes phpmyadmin to break. I have not had any issues with 5.3.1 other than this so far and hopefully somebody will find a way to get the newer version of php working. I'm running Vista Home Premium 32-bit and most others with this issue seem to be using Vista or 7 so perhaps there's a connection there. Hope this helps.
I am very new at all of this. I have been teaching myself how to work with code and now with PHP. I ran into the same problem and spent several hours looking for a solution. My problem is that I am running win 7 64 bit. Here is the fix if this is your problem:
In the config.inc.php file you need to change
$cfg[$i]['host'] = 'localhost'; to $cfg['Servers'][$i]['host'] = '127.0.0.1';
For some reason they are not recognized by Windows 7 as being the same. (it runs fine without the change on my XP machine)
I found this informaitn on another forum, hope it helps.
