.Net Application getting crashed in production with System.IO.FileNotFoundException

.NetApplication is getting crashed with below stacktrace in one of production server. While digging it over various developer forums, I found that this could be bacause any custom exception thrown by different AppDomain is not getting handled in other AppDomain. But I am confused with this as I have defined the custom exceptions which could be raised.I have defined deserialization constructor also for exception propagation to other AppDomains. Please suggest something.

System.IO.FileNotFoundException: File or assembly name Product, or one of its dependencies, was not found. File name: "Product"

     at System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase,
Boolean isStringized, Evidence assemblySecurity, Boolean
throwOnFileNotFound, Assembly locationHint, StackCrawlMark& stackMark)
at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Boolean
stringized, Evidence assemblySecurity, StackCrawlMark& stackMark)
at System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence
assemblySecurity, StackCrawlMark& stackMark)
at System.Reflection.Assembly.Load(String assemblyString)
at System.Reflection.MemberInfoSerializationHolder..ctor(SerializationInfo
info, StreamingContext context)
at System.Exception.GetExceptionMethodFromString()
at System.Exception.GetTargetSiteInternal()
at System.Exception.get_TargetSite()
at ID.Components.Exceptions.IDTException.ToString()
at ID.UI.IDTecControls.IDTDialogBox.ShowErrorDialog(String
showOnlyMessage, Exception e, String pluginName, String pluginVersion,
String methodName)
at ITI.Plugins.Side.btnNew_Click(Object sender, EventArgs e)
at System.Windows.Forms.Control.onclick(EventArgs e)
at System.Windows.Forms.Button.onclick(EventArgs e)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr
wparam, IntPtr lparam)