Avast will not open for setup

Hi Guys,
I downloaded Avast but when I click to setup I get this message:
An error 0(00000000) has occurred.
Last performed operation was:spawning. Hope you can help,as now have no protection.
Regards,
jimindigo :-\

what antivirus did you use before avast?
have you removed it before installing avast?
did you run the vendors removal tool to clear any leftover files that may conflict?

Successfully Installing avast! Free