Hoa Javito25. Bienvenido al foro.
There is an all Spanish Forum here:
http://forum.avast.com/index.php?board=25.0¿ What Windows; Spk, bit ?
¿ Which avast! and Program version ?
Which Shield or how is the file being detected ?
If it is during a regular scan, avast! should open a window with the result so you can choose what to do with the files detected.
For the shields you can open their options and change the action if something is detected. Web shield is set to abort connection and it should stay like that.
Open avast! > Options > Active protecion > File System Shield > Click gear icon > Actions
see image