20080618 - Error connecting to undo manager of source file

Visual Studio 2008 提示：
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Microsoft Visual Studio
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Error connecting to undo manager of source file 'E:\Work\ITIL.SD\trunk\code\SDWeb\Default.aspx.designer.cs'.
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确定  
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解决办法：
例如：对于 Default.Aspx
右键删除 Default.aspx.designer.cs
右键点击 Default.Aspx，选择 Convert to Web Application