I'm having the same problem as everyone above. The box comes up saying to enter a 4-6 digit number, and red letters saying "PIN Recovery not set. Please set the recovery phone number in the settings." I can see "Settings" in the menu list right behind the message to "Enter avast PIN number" but it's all grayed out and you can't even access settings without first entering the PIN!! Did I explain it well enough that you can at least picture the problem here now? I decided to just uninstall the whole thing and go with a different mobile security company, but the damned thing won't even let me uninstall without -- you guessed it, the PIN number!!! It's awful being stuck with NO mobile security except one you can't even use OR uninstall!! I have a Sony Xperia Arc S LT18a. PLEASE someone explain in English what the heck to do now besides throw this new phone in the river. Thank you.
Udate: I got it fixed. I turned off the phone, took out the battery, and started over. Now it works fine - coincidence, I'm sure. Now I have another problem. I have avast in stealth mode, renamed it something a thief wouldn't associate with a security system, etc. Let's just pretend I named the fake file "jellybean." Now on the apps page it shows the jellybean icon sitting right next to the avast icon. I tried dragging and dropping avast into jellybean and it doesn't work. It's certainly not going to confuse a thief like this!