This is something related to D3 but not IN D3 gameplay:

I was using mobile authenticator to login to D3. YTD I did a factory reset (Phone upgrade to ICS) to my phone and I didn't uninstall the mobile app prior to phone reset.
The newly install BNet app after phone reset does not carry the same serial anymore and I didn't take down the previous serial/restore code.

Now I am locked from the Door to Hell.

Filled in form @ battlenet and gotta wait for them to restore for me. I am saved from D3 during the weekend.

Suggestion: next time write the restore code down and store it alongside with your precious D3 CD.