Revolving procedure

I have the free AVAST Antivirus and for the past 2 years has worked flawlessly. Suddenly out of nowhere I have this new problem, I also notice that the look of AVAST has changed so I am guessing it has updated itself. So besides running a quick scan which works, anything else I try whether changing setting, run a full scan or whatever I get this window that reads the following;

"An attempt has been made to enter a protected area of AVAST (Program Settings) This may be a legitimate action, but could also be the result of a malware attack.

Do you want to continue?

(Select cancel if you are performing this action intentionally)"
Then you have a continue button and a cancel button that is counting down from 59 seconds. Above these 2 buttons, you have a Password box and I have tried every password I can find online and nothing work. I removed AVAST from my computer and tried to reinstall it but only to have the same results. I removed again and used another well-known anti-virus and it came back clean and free of all virus, worms etc. I then reinstalled AVAST as it has always worked best for me and yet again the same thing.
Could someone please help before I rip out all my hair. Thanks in advance as I am sure its something so simple and stupid.

-Jair.

Perform a clean installation of the latest avast version.