ASP.NET 2.0 intermittent referencing errors

[Guest]

I'm having a problem in my web pages where I am intermittently getting build
errors like:

'Public Sub Add(item As System.Web.UI.Control)' is declared in project
'App_Web_qjc9qqwr.dll', which is not referenced by project
'10_home_Home.aspx'. Add a reference to 'App_Web_qjc9qqwr.dll' to your
project '10_home_Home.aspx'

I assume App_Web_qjc9qqwr.dll is some kind of autogenerated temporary dll
and '10_home_Home.aspx' is another autogenerated file.

How do I get past this?