designer errors: Object reference not set to an instance of an object

I am getting the following error when I try to open the designer for some of the forms in my project. I have no
clue why this is happening.

thanks

Object reference not set to an instance of an object.

at Microsoft.CompactFramework.Design.DeviceTypeResolutionService.EnsurePopulated(Boolean fPopulateProject) at Microsoft.CompactFramework.Design.DeviceTypeResolutionService.SearchNormalEntries(AssemblyName assemblyName, String typeName, Boolean ignoreTypeCase, Boolean reflectionBased, Assembly& assembly) at Microsoft.CompactFramework.Design.DeviceTypeResolutionService.SearchEntries(AssemblyName assemblyName, String typeName, Boolean ignoreTypeCase, Boolean reflectionBased, Assembly& assembly) at Microsoft.CompactFramework.Design.DeviceTypeResolutionService.GetDeviceType(String typeName, Boolean throwOnError, Boolean ignoreCase) at Microsoft.CompactFramework.Design.DeviceTypeResolutionService.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, ReferenceType refType) at Microsoft.VisualStudio.Design.Serialization.CodeDom.AggregateTypeResolutionService.GetType(String name, Boolean throwOnError, Boolean ignoreCase) at Microsoft.VisualStudio.Design.Serialization.CodeDom.AggregateTypeResolutionService.GetType(String name) at System.ComponentModel.Design.DesignerHost.System.ComponentModel.Design.IDesignerHost.GetType(String typeName) at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.EnsureDocument(IDesignerSerializationManager manager) at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager manager) at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager) at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.DeferredLoadHandler.Microsoft.VisualStudio.TextManager.Interop.IVsTextBufferDataEvents.OnLoadCompleted(Int32 fReload)

解决方案：

For a C# project I followed what mtm_king said + deleted the <project_name>.csproj.user file. And everything works
fine now

原帖链接：http://social.msdn.microsoft.com/Forums/en/winformsdesigner/thread/4ceb2dd3-c760-495f-83e6-1bf2a54fda93