Avast doesn't start!!

I just downloaded Avast Home Free and after register, I try to run the program, scaning or any other action and the message below appears.
This is the third time I download it and the problem remains…
If anyone knows how to fix it, please write: cacadocinho@hotmail.com

Thank you.
Camila

ASHSIMPL causou uma falha de página inválida no
módulo em 0000:1b10ec7d.
Registros:
EAX=03ebff88 CS=0167 EIP=1b10ec7d EFLGS=00010246
EBX=03ebff88 SS=016f ESP=03dc0104 EBP=03dc0124
ECX=03dc01a8 DS=016f ESI=81777db0 FS=4467
EDX=bff76855 ES=016f EDI=03dc01d0 GS=0000
Bytes em CS:EIP:

Check this post, please.