Interesting. I looked under control Panel ->Uninstall program and I found two 3CX Myphone, one is localhost and the second 192.168.100.26 which was my laptop static IP. So I uninstalled both and reboot.
On the fresh boot, I launched a Firefox browser and this time on navigating to
http://192.168.100.26:5000/myphone I entered the extension and Pin
AND tick the remember me button. Previously I never tick the remember me button on the browser version because I knew I was going to install the desktop component immediately. I thought I will tick the remember me checkbox in the silverlight version of myphone.
So this time after ticking the remember me in the browser version of myphone, installed the desktop component, checked that the control panel only shows 1 myphone (which is the static 192.168.100.26), checked silverlight has the storage space allocated as shown, I shutdown the laptop. Next day when I boot up the laptop the Myphone (silverlight) logged in automatically.

I am running 3cx v 10 with SP2, 3cx phone v6, myphone (silverlight), win 7 x64.