Because of thread application is getting hanged

//This is declared Globally
 Thread TrdCopyFLV=new TrdCopyFLV();

//this is called in a timer
if (TrdCopyFLV == null || !TrdCopyFLV.IsAlive)
                   {
                       //TrdCopyFLV = new Thread(delegate() { ConvertToFlv(lOpr1, lOpr2); });
                       TrdCopyFLV = new Thread(ThreadConvertToFlv);
                       TrdCopyFLV.IsBackground = true;
                       TrdCopyFLV.Priority = ThreadPriority.Lowest;
                       TrdCopyFLV.Start();
                   }