Cannot install iTune and avast

I got the "Unknown Publisher" warning each time I tried to install iTune or
avast. When I choose OK, the warning disappeared but did not install the
software.

Anything I should check? Any help will be grateful.

My OS is Windows XP pro with all latest updates.

I downloaded itunes 7.6.2 but cannot open it. I got one error, "unable to
start winScard.dll not found", the rest of the attempts just went nowhere.
When I update my xp account "Advantage Validation Tool(KB892130) does not
download. I think the 2 might be related and I don't know how to fix either.
Thank you for any help, Linda

"zerone" wrote:

> I got the "Unknown Publisher" warning each time I tried to install iTune or
> avast. When I choose OK, the warning disappeared but did not install the
> software.
>
> Anything I should check? Any help will be grateful.
>
> My OS is Windows XP pro with all latest updates.