Failed to initialize storage module- PHP error -IIS

PHP Error  :

Fatal error: session_start() [function.session-start]: Failed to initialize storage module: files (path: )

Solution:

Uncomment   session.save_path =    line  and define the tmp folder for example “C:\tmp” , so  the line looks like

session.save_path =  “C:\tmp”

Also make sure that tmp directory is writable by IIS user