Hi Telerik Full version number of the Telerik control or product being used: 2013.3.1324.45 Operating system details of your development machine/server: Win8.1 / Windows Server 2012 / Windows Server 2008 R2 Browser type and version number (where applicable): IE11 // FF IDE Edition (Including Service Packs): VS 2013 / VS 2012 Update / SP 4 Preferred coding language: C# Possible duplicate of this Declined issue: http://feedback.telerik.com/Project/108/Feedback/Details/39250-fix-radscheduler-throws-specified-argument-was-out-of-the-range-of-valid-values I run into exactly this problem in my application. if my users changes from dayview to week or month views, depending on number of resources. I have not tested this for the other horizontal grouping enabled views multiday and timeline. Is it posible for a fix that reduces to a max value like 32767, when calculating or setting the table width. part of my code: RadScheduler1.ColumnWidth = new Unit(200, UnitType.Pixel); //Note will cause exception when many resources //and Telerik.Web.UI.GroupingDirection.Horizontal //The Unit class can represent values only between -32768 and 32767 Stack trace: Specified argument was out of the range of valid values. Parameter name: value at System.Web.UI.WebControls.Unit..ctor(Double value, UnitType type) at Telerik.Web.UI.Scheduler.Views.SchedulerRenderer.SetContentTableWidth(Table contentTable) at Telerik.Web.UI.Scheduler.Views.SchedulerRenderer.AddHorizontalHeaders(SchedulerTopTable topTable) at Telerik.Web.UI.Scheduler.Views.Month.GroupedByResource.Renderer.GetInnerContent() at Telerik.Web.UI.Scheduler.Views.SchedulerRenderer.GetContent() at Telerik.Web.UI.RadScheduler.CreateContent() at Telerik.Web.UI.RadScheduler.CreateChildControls(Boolean bindFromDataSource) at Telerik.Web.UI.RadScheduler.CreateChildControls() at System.Web.UI.Control.EnsureChildControls() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) Regards Peter