i need to disable autobox in avast 8
how can i do it?
From the file shield>settings>autosandbox>untick the box 
Is there a specific reason for this ?
e.g. if for one particular program you can have it excluded. You can also report it as a false positive.
If it is for all occurrences, this really is a poor security decision, You can do as Para-Noid (and I have) has and set it to ASK, this gives you executive control over it. Whilst this may result in more pop-ups asking if this should be run/analysed in the AutoSandbox. You obviously have to know what you have installed on your system and what you have just downloaded, etc.
@ DavidR Thanks, I should have explained the risks involved with a disabled autosandbox. :-[
The users that i’m installing the anti virus does not know how to use it so I prefer to disable it.
They do have the ability to set the autosandbox to “auto-decide”.
It is a valuable tool with the new signatures that are used in conjunction with it, so Auto-Decide as Para-Noid mentioned may well be better.