After I installed Avast (latest edition) I now have a Windows security icon in my system try telling me I have no antivrus software installed and that Avast is reporting I have an old edtion and to upgrade, which is obviously wroing.
First check your system date, especially the day month and year, correct if required.
That should deal with the out of date error. The no AV installed is another matter a common problem (fault) with Windows Security Center in winXP (I assume you are using Vista ?) that would appear to have been inherited by Vista.