Pages don't always show when using cfinclude

For our site we have a page template, a shell, that we use to display pages. It uses a cfinclude to call the page into the template:

<cfinclude page=#url.PageName#.cfm>

The link for that page would look like:

<a href="index.cfm?PageName=contact">

However, on a number of occassions, users click a link for a page, and get the error "page not found". If they simply hit refresh, the page shows up without a problem. The page is there, and it works, but it just doesn't always show until refreshed. Of course, most users don't know to refresh, and it's a pain to do anyway.

Any ideas why this happens? Suggested solutions?

Thanks,
Tim