Annie, removing the quarantined items from SAS should take care of the "avast can't scan - password protected archive" issue. as for the rest, I have no first-hand advice to offer:   I have no problems starting avast 4.8 and opening its "chest" (avast's name for "quarantine")... albeit my "chest" is empty. you indicated using ZoneAlarm... I'm using Comodo... but I don't know if that's making any difference here. EDIT:   the first obvious thing to check is make sure you have the lastest avast build, 1296.   (if you prefer, 4.8.1296)    there was a short-lived build 1287 which had a bug in it.   i can't say that's the cause of your problem, but it's certainly best to take simple steps to rule it out. if i were you, before trying an uninstall/reinstall of avast, i would post your problem [including system configuration, like your firewall] at the avast forum: [URL] i've generally found the people there to be very helpful/cooperative. in terms of an 11 hour scan, i'll admit that seems very long.    but scan time is dependent on so many factors, including processor (CPU) speed, disk speed (rpm, DMA), number of files being scanned, as well as the nature of the scan:   avast offers a quick, standard, and thorough scan ; which can include or skip-over archives.   a thorough scan, including archives, would take the longest time.   but even so, 11 hrs??? if the avast forum can't help you, then i'd try a uninstall/reinstall.
When running an antivirus scan using the lastest AVAST program 4.8), at the end of the scan an Action window appears with a lot of files that say "unable to scan: Archive is password protected." These files all seem to have something to do with the program SuperAntiSpyware?  Anyone know what this might mean and why these files are not being scanned?  
AVAST-UNable to scan: