Oracle client and program access denied

I have purchased 3 new computers all with Vista Business installed. We run a
Oracle based application. When I attempt to run the application, once I enter
my login information (for Oracle) I get an access denied message. I am
assuming this is related to some sort of security issue, but I have logged on
as Administrator for the domain, tried different users that I have put in the
domain admin group. Set the domain\administrator as the owner at the root of
c: and subdirectories. Turned off firewall, turned off user account control,
turned off windows defender, and so on. Does anybody have an idea of how to
get this to work.

Thank you
Tim