Hi...
I'm not familiar with Alwil sending a CD for installing avast, even for the professional version. From whom did you receive this CD and is it possible you are referring to the BART CD?
Although it may be innocent and part of some "freeware utilities" CD, I would be cautious of installing software from an unknown and/or unofficial source.
If you are looking for the free home version, please go
here and register first.
Then go to this
page and download avast in the language of your choice. After a while, check your e-mail for the program key and follow the instructions in this
video tutorial. Hope this helps.
May God Bless you!