Can't Change Security Settings in Explorer

[TeachR]

I cannot change certain security settings in Explorer. I've gone to Tools->Internet Options->Security Tab, and the custom level button is greyed out on all the choices here.

I am running Internet Explorer 6.0 and Windows 98 SE. McAfee Virusscan version 6 is installed on my computer, and I've got all the latest "critical updates" for my Windows System and the latest patches for Explorer.

Any ideas? Thanks.

A.A.

 

[carrr]

IS this a home/stand-alond pc or a work/on a network pc?
i.e. Is there, for some reason, a preconfigured IE load on this machine?

 

[TeachR]

This is a stand-alone PC at home, and always has been. I'm the only logged on user, although others have used this computer.
P.S. This is the first time I've tried to change security settings; I have no idea how long the settings have been this way.
A.A.