Well, I admit we don't have much experience with Chinese Windows.
I don't exactly understand what "it wraps up" mean, but I suppose it stops or freezes somehow.
Could you try to find out if the scanning stops on a particular file (e.g. because it has some "strange" filename avast cannot handle, or because it has some strange content avast has problems with)? You can try scanning just a directory, then another one... and check if the scanning freezes really just on one (or a few files) or if is stops always, on any directory.
You can also try to switch on the creation of the Report file (in Settings) - if you configure the "OK files" to be included in the report, you can see (in the report) the last file that was successfully scanned, i.e. the problematic file would be the one "following". This way, you can see if it stops always on the same file (and if yes, it helps you to identify the "problematic" file).
Let us know, please, what you find out. By the way, what operating system do you have? (I understand it's Chinese, but is it Windows 98, 2000, XP, ...?)
