I have spent 3 hours today to install PEAR on Windows. I had systematically the error, when I was trying to execute config-set auto_discover 1 in the CMD:
PEAR_Config::writeConfigFile fopen('C:/Windows/pear.ini', 'w') failed... permission denied
It was clear that the problem in the PEAR installation - the location of pear.ini file was wrong. It's important to note, that all installation and manipulation with pear I made with basic CMD.
If you have the same problems, you have to reinstall your PEAR with PowerShell.
With PowerShell the pear.ini is in the PHP folder and it will fixe all the problems