WampServer

I get "Invalid Server Index" error every time I start up. I get it fixed and all is well, then the next day when I bootup, it's back.
MySQL service IS running and I've tried various recommended changes to the config.inc file.
The first day worked with this:

<?php
$cfg['Servers'][$i]['extension'] = 'mysqli';
$cfg['Servers'][$i]['password'] = 'password';
?>

Next day, Invalid Server Error. I researched and found suggestions to change the file, which worked -- until the next bootup.

<?php
$i++;
$cfg['Servers'][$i]['extension'] = 'mysqli';
$cfg['Servers'][$i]['host'] = 'localhost';
$cfg['Servers'][$i]['password'] = 'password';
?>

Today, I get the error again. I've tried all kinds of other changes but nothing is working. I'm on one PC with XP Pro, hoping to establish a stable testing environment for CMS template design. I'm new to MySQL and PHP.

What shall I try now?
Thank you.