CRM 2011 - Form Loading Error

Error Message: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Error Details: Exception of type 'System.Web.HttpUnhandledException' was thrown. Source File: Not available Line Number: Not available Request URL: https://devfia.readymembership.com:4433/userdefined/edit.aspx?_gridType=1&etc=1&id=%7b702EC9A0-B3FF-E011-9548-87FF2896E5A3%7d&pagemode=iframe&rskey=894977316&sitemappath=Workplace%7cMyWork%7cnav_dashboards Stack Trace Info: [NullReferenceException: Object reference not set to an instance of an object.] at Microsoft.Crm.Application.Controls.AppNavigationBar.CreateOrderedAreas(NavPaneItems navPaneItems)

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To Resolve This Import Customization Again as Manage Solution.