Exactly the same error. Just can't find a resource to fix this one. It doesn't seem to log anything that I can find. Happens when I go to the WebPart Gallery and hit NEW. If you guys ever found the fix, I'd be very happy to hear it Here it is: File Not Found. at System.Reflection.CustomAttribute._CreateCaObject(Void* pModule, Void* pCtor, Byte** ppBlob, Byte* pEndBlob, Int32* pcNamedArgs) at System.Reflection.CustomAttribute.CreateCaObject(Module module, RuntimeMethodHandle ctor, IntPtr& blob, IntPtr blobEnd, Int32& namedArgs) at System.Reflection.CustomAttribute.GetCustomAttributes(Module decoratedModule, Int32 decoratedMetadataToken, Int32 pcaCount, RuntimeType attributeFilterType, Boolean mustBeInheritable, IList derivedAttributes) at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeType type, RuntimeType caType, Boolean inherit) at Microsoft.SharePoint.WebPartPages.SPWebPartManager.GetEffectiveWebPartType(Type webPartType, SerializationTarget serializationTarget, Boolean ignoreSupportsAttributeMarkup) at Microsoft.SharePoint.WebPartPages.SPWebPartManager.GetEffectiveWebPartType(Type aspWebPartType, SerializationTarget serializationTarget) at Microsoft.SharePoint.ApplicationPages.NewDwp.Page_PreRender(Object sender, EventArgs e) at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) at System.Web.UI.Control.OnPreRender(EventArgs e) at Microsoft.SharePoint.WebControls.UnsecuredLayoutsPageBase.OnPreRender(EventArgs e) at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)