TO MANUALY DISABLE THE COMPLETE/FINISH UPDATE DIALOG BOX FROM POPING UP EVERY BOOT.
GO TO THIS PATH
C:\Documents and Settings\All Users,WINDOWS\Application Data\AVAST Software\Avast\avast5.ini
In the .ini file find the line: ShowSetupOutro=0 :and make shure it is set to =0 as shown here.
AND NOT this path:
C:\Documents and Settings\All Users,WINDOWS\Application Data\Alwil Software\avast5.ini
this path will not offer ShowSetupOutro=0 in the avast5.ini file, and adding it will not work.
REMEMBER to click away dialog boxes to bypass Avast's, self protection, or go to the programs options to allow this. There is also booting in safe mode.
I Got the instructions from another member but I added the path correction for my system, and it worked. Probably because I was upgrading from previous versions. A brand new installation might not require the caution about the path.