Well,

I have done this and it worked for me!
I did applied the aswClear, but in Safe mode, and reinstalled and PC froze again. So I did what essexboy told, uninstalled without go to Safe mode disconnected from the net, and installed the LAST update. I had an version of last week, I don’t know if today’s version is new.
The difference is that previously, when I installed Avast, it asked to scan the system before starting, and then was when it froze the PC. With this last version it didn’t ask to scan the system, and started directly. I don’t know if this is good, but now Avast is working fine.

Thank you!