多线程，调用其他线程控件问题

[流言蜚语]

异常描述：由于以前的函数求值超时，函数求值被禁用。必须继续执行才能重新启用函数求值。

        private void builder_BuildProgressChanged(System.Int32 progress, System.String state)
        {
            if (this.lvwInstance.InvokeRequired)
            {
                this.lvwInstance.Invoke(this.SetInstanceState, new System.Object[] { progress as System.Object, state as System.Object });    // 该行报异常：NullReferenceException
            }
            else
            {
                this.SetInstanceState(progress, state);
            }
            if (this.pgbBuild.InvokeRequired)
            {
                this.pgbBuild.Invoke(this.SetProgress, new System.Object[] { (progress + 1) as System.Object });
            }
            else
            {
                this.SetProgress(progress + 1);
            }
        }

        private delegate void SetInstanceCallBack(System.Int32 index, System.String state);
        private SetInstanceCallBack SetInstanceState;
        private delegate void SetProgressCallBack(System.Int32 progress);
        private SetProgressCallBack SetProgress;

        private void _SetInstanceState(System.Int32 index, System.String state)
        {
            this.lvwInstance.Items[index].SubItems["colState"].Text = state;
        }

        private void _SetProgress(System.Int32 progress)
        {
            if (progress < 0)
            {
                this.pgbBuild.Value = 0;
            }
            else if (progress > this.pgbBuild.Maximum)
            {
                this.pgbBuild.Value = this.pgbBuild.Maximum;
            }
            else
            {
                this.pgbBuild.Value = progress;
            }
        }

报的是空引用异常，但是所有控件均有值，个人怀疑是ListView中的ListViewItem问题。
求异常原因和解决方案。