WinForm designer error open designer

I work on VS 2010 .net 4.0 , my app had winForm with many controls. sometime i occur very starnge designer error:

Could not find type 'Namespace.TypeName'. Please make sure that the assembly that contains this type is referenced. If this type is a part o开发者_JAVA百科f your development project, make sure that the project has been successfully built. The variable 'ControlName' is either undeclared or was never assigned.

i click Ignore and Continue the control disappear from my form. if i look in designer.cs the controls are exists..

I read this : link text but it is in vs2003 and i can not sucess solve this problem..

Thanks..

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This problem can be caused in a number of ways, usually by custom controls/components that:

• Do not have a default constructor
• Depend on variables that are set at run-time (singleton instances, data sources, etc)
• Fail to compile (you can't use a control in the designer until it compiles successfully)
• Have been significantly changed/rewritten since they were added to the form

It can also happen as a result of a glitch in Visual Studio - this is much rarer, but can usually be fixed by cleaning and rebuilding your solution and/or restarting the IDE.