This red sign over the avast icon is often an indication of another AV installed on your system or previously installed.
Have you or did you have another AV installed on your system - if so what was it and how was it removed ?
However, since you were running avast 4.6 OK that may not be the case. I have seen this reported once (after updating from 4.6 to 4.7) in the forums and it required the user to reboot more than once before this was resolved, give that a try.
Your English is fine, welcome to the forums.