The stub cannot load installer etc. Money wasted. Newly purchased anti-virus pro.
Please help.
What OS/SP ?
What exact version of avast ?
Is there any other security (related) software installed ? (or was there)
You could try the off-line setup file instead.
Use the direct download setup file avast pro version.
https://forum.avast.com/index.php?topic=189836.0
Avast Pro off-line installation file - http://files.avast.com/iavs9x/avast_pro_antivirus_setup_offline.exe
If you do have a previous AV as Eddy asks, you need to remove it before installing avast.
It has been suggested that you may be running Microsoft Vista, can you confirm this and the other questions asked by Eddy.