The output file is too big and then it will display a red box. Please try to reduce the panorama output size. On the Select Photos step, please select 1/4 Size or 1/16 Size from the Output Size drop-down list. The Original Size is for printing.
From the Save dialog box, choose the High Compression setting from the Quality drop-down list box. A lower quality setting saves a smaller sized file whereas a larger quality setting saves a larger file size.