How to de-activate the auto-locking feature on Nokia E66

My mum just got this Nokia E56 and it had a problem. The auto locking feature was enabled and it was impossible seemingly to turn it off. That meant that after every 20 mins of non usage, it tend to lock itself and will require I enter the 5 digit unlock code for Nokia (12345) to unlock it.

I tried to turn off the auto lock feature but it was giving me the error "Unable to unlock phone".

I went from the Menu > Tools > Settings > General > Security > Phone and SIM card > Phone autolock period, tried to choose "None" I got the error: "Unable to unlock phone".

It kept on giving the error each time I wanted to change it from user defined to None but was not giving me an option to enter the unlock code. I tried changing the unlock code and that worked but I was still unable to turn off the phone autolocking feature for the Nokia E66.

I guess it must have been a firmware problem and so the last option was to reset it to factory settings.

First things first before I went for the factory setting reset was to do a back up of local settings, contacts and messages that were already on the phone and that I did by using the Nokia pc suite on my computer.

After doing the back up, the next thing was to reset factory settings.

Resetting factory settings did the trick and it reset the Nokia e66 phone as if it just had a brand new life and besides, the autolock feature already came disabled and now the phone works as normal.