can’t add a trusted site in IE7

As part of accessing our site we encourage customers to add us as a trusted site. 99% of the time this works fine. Since IE7 came out we keep getting people who no matter what we try cannot get IE to recognise it as being in the trusted sites zone.

We’ve tried removing all references, and re-adding. Adding with the whole URL or generic versions. No matter what we just can’t get it to show up as a trusted site in the status bar.

Has anyone else come across this problem?

Cheers,
Mike