Sungame: There may be many different problems. You have two ways:
a) wait for my help
b) uninstall avast, download latest setup and reinstall.
In both cases, I would like to get your setup.log file, which resides in avast4\setup directory. I would also like to know what os/language are you using. Please send it to my address: kubecj at asw DoT cz
thanks,