ell, try this and perhaps it might help you find your way out : sit back & relax..
i've tried these steps below, and it works on my WIN-XP
1. make sure you have installed the 'Preinstalled Utilities' first !!
the utilities could be found in :
Welcome : Support for Sony
2. you need the 'HotKey Utility' running on your system
here's i found some version of 'Hotkey Utility' in :
ftp://ftp.vaio-link.com/PUB/Vaio/hotkey/
i used the newest version (SONYUTILS_HOTKEY_10_ENG.ZIP), and.. gee, now i love to press my fn+f4 for mostly times
if you running an upgraded OS, you may check this hotkey utility services whether it's already running in background or not
in Windows Task Manager (ctrl+alt+del), find the proccessing files named HKwnd.exe & HKserv.exe. if those files exist
but your fn+key still not working, then it might be there's a compatibility problem with your newer OS version. so i think that
you will need to upgrading the utilities
ow..yaa, don't forget to restart your pc after installing,
and make sure a 'start up item' in System Configuration Utility (run msconfig.exe) named 'HKserv' is enabled (default)