Yes a boot-time scan includes the rootkit scan, however a Quick scan in the Simple User Interface doesn't (only Standard and Thorough include it).
ok i remembered well (read somewhere)
so it is almost impossible to understand why avast locks up in standard and through mode i think (they lock in windows dir but other antivirus do not lock up and this lock up wasnì't present time ago maybe before the rotkit scan , who knows ?),anyway boot scan , quick and scan with other antivirus are all ok
at least i have discovered that my mail was not protected and i solved it
i prefer avast anyway , has blocked those few dangers i met and has solved with a network scan a huge problem in another pc with another antivirus that was fooled by a bad virus