So here’s the scenario, your designing a SharePoint Application Page or similar and you want to inherit from one of the SharePoint Master Pages (e.g.application.master).
It seems if you choose to use VS2008 to do this, you will run into a problem. VS2008 will not display the aspx page in the designer and will throw an error that the masterpage cannot be found, correct the problem in code view. As far as I can tell there is no fix for this and you would need to design the page in code view which is quite frustrating.
I have found a few threads on MSDN detailing the problem, see here:
The only real solution is to use VS2005, it will present you with a warning saying it cannot find the masterpage but will still show generic placeholders on the page and allow you to design the page in design view. This is what I am currently doing.
If anyone has a solution or a fix for the above problem, please let me know!