I too facing the same issue. while exporting the data from grid to excel i am using the below code...
Dim spreadExporter As Telerik.WinControls.Export.GridViewSpreadExport = New Telerik.WinControls.Export.GridViewSpreadExport(griddata)
spreadExporter.ExportHierarchy = True
spreadExporter.ExportVisualSettings = True
If the column data is more i am not able to export. it is showing the error "code--2146233086:columnWidth should be greater or equal than 0 and less or equal than 2000."
But if "spreadExporter.ExportVisualSettings = False" able to export but the excel format getting disturbed.