Visual Studio :: Intellisense Not Working For Nested Master Page?

I am using Visual Studio 2008 SP1

I have two master pages: TopLevelMaster and NestedMaster

When my page points to NestedMaster as it's master page, intellisense quits working in the .aspx page.

If I change my page to use TopLevelMaster as it's master page, intellisense works.

No matter what I use as the master I always get a green squiggly underline under the Content control that brings up a tooltip that says "Could not find ContentPlaceHolder1" in the current master page or pages"

TopLevelMaster exists in a different project than NestedMaster and the page.

When I say "intellisense quits working" here is what happens:

If I type something between the Content tags I get no intellisense for asp controls:

<asp:Content ID="Content1" runat="server" etc.., etc..>

Only html controls appear upon typing an open angle bracket here

</asp:Content>

If I instert a div element I can type an opening angle bracket and I see a list of all asp controls. If I choose one and start typing there is no intellisense after that:

<asp:Content ID="Content1" runat="server" etc.., etc..>
<div>
ASP controls appear but no intellisense other than asp:ControlName
</div>
</asp:Content>

Opening one or both master pages in the IDE has no effect.

I deleted Visual Sudio temp files.