Cookie Won't Persist In IE

(I'm not sure if this is the right forum for my post - my question is about vbscript, but I didn't see any vbscript forum, so here goes.)

I've created a registration page on my website which gets called from a number of links on the site - I want to capture user information before allowing them access to these sections of the site.

Once a user has registered, I want to recognise that fact when they click on any of the other links, so I'm setting a cookie. However, while it works fine in Firefox, it won't persist in IE - even across a single session.

Here's the code I'm using :

In the 'Thank you for registering' page, the very first lines on the page are :

<%
Response.Cookies("Registered") = "True"
Response.Cookies("Registered").Expires = Date + 1000
%>

Where the links that require registration appear on the site, I am building the <a href> tag as follows :
<a href=
<% if Request.Cookies("Registered") = "True" then %>
"PageX.asp"
<% else %>
"Register.asp?RequestedArea=ReportDesign"
<% end if %>
class="bodyLink">Report Design</a>

but it keeps going to the Else part - ie. it's not finding that the Registered cookie has a value of True.