hello paul,
could you please start a new topic.

its kinda different from the this topic.
well you can do this:
lets try this :
0. download the offline avast installer from here :
http://www.avast.com/eng/download-avast-professional.html , please use the full installer. do not download the online installer and also from cnet (download from avast site itself). select the required language.
1. download avast uninstall utility from here:
http://files.avast.com/files/eng/aswclear.exedisconnect from the internet.
2. Start Windows in Safe Mode.
3. Run the uninstall utility (If you installed avast! in a different folder than the default, browse for it)
4. Remove
5. Restart your computer.
6. install using the brand new installer you download in step 0.
7. restart.
8. insert pro key.
9. update av.
10. check whether the new key is applied.
how to insert key :
http://www.avast.com/files/tutorials/insert_key.htm