If you encounter situation like below on your s60v2, 
1. Blank screen phone unable to reboot.


2. Phone only able to boot-up to "Nokia" word screen.


3. Install some program but notable to uninstall it after that.


4. Error messages such as"Child Installer" keeps popping-up.Do a Full phone formatting on your 6600! as steps below,


1. Make sure you have at least 3/4 charge of battery power left.


2. Backup your contacts list and personal files to MMC memory card.


3. Switch-off your 6600 phone.


4. Press and hold 3 keys;Green dial key, * (star key) & no. 3 key and then press the power on/off to swtich on the 6600 phone.Remember, do not let go all of the keys and hold keys until you see a formatting word screen show!


5. After a few minutes when the Full phone formatting completed, your 6600 will backto original system and factory settting.


All apps installed & not of the phones' default will be lost. If you did a backup on your mmc,you can restore it back to the C drive again.