Avast 4 Professional Edition/ Setup Selfextract

I am trying to install Avast 4 Professional Edition and it(he,she) indicates me this notification of the image of the low part and does not leave me to continue with the operation, might I help? Thank you

The installer is probably corrupted. You may try re-downloading an avast installer at avast! website.

Yes, I am trying(mean) it instlar from the unload in Avast’s web and it indicates this to me.
Some another solution to my problem?