C# windows application hang after some time

my windows application hang after some time 

private Thread objnewth;

if (objnewth == null || !objnewth.IsAlive)
                {
                    objnewth = new Thread(new ThreadStart(objmain.backgroundprocess));
                    objnewth.IsBackground = true;
                    objnewth.Priority = ThreadPriority.Highest;
                    objnewth.Start();
                    //backgroundprocess();
                    BtnStartStop.Text = "Count:-" + theCount;
                    timer1.Stop();
                    timer1.Start();
                }