MSBuild problem

When running a build using MSBuild (.NET Framework 2.0) I am getting
the following error appearing:
error BC30610: Class 'FrontPage' must either be declared
'MustInherit' or override the following inherited 'MustOverride'
member(s):
d:\builds\internet\mainstream\FrontEnd\Motorbike
\Proposer1.aspx.designer.vb(22):

This is using a build file that contains the data:








If I build the solution on the same machine using Visual Studio 2005
then it builds with no problems.

The classes that cause that error are code behind pages that inherit
from a generic base page class that uses generics. This base page
class has a MustOverride member in it. Some sample code:

Public MustInherit Class AMBPage(Of P As IPresenter)
Inherits ABasePage(Of P, IMBWebApplicationController)

Public MustOverride Overrides Function CreatePresenter() As P
End Class

Partial Public Class FrontPage
Inherits AMBPage(Of FrontPagePresenter)
Implements IFrontPageView

#Region " Overrides "

'''