trouble uploading media

I’ve been trying to upload media to a new gallery and the thumbnails aren’t displaying properly. In substitute either a black “X” or a clip art image shows up. If I try to edit the thumbnail this shows up. Any ideas?

Warning: imagecreatefromjpeg() [function.imagecreatefromjpeg]: gd-jpeg, libjpeg: recoverable error: Premature end of JPEG file in /home/silversp/public_html/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/lib/gd.thumbnail.inc.php on line 179

Warning: imagecreatefromjpeg() [function.imagecreatefromjpeg]: ‘/home/silversp/public_html/wp-content/gallery/new-patients/DSCN0156.JPG’ is not a valid JPEG file in /home/silversp/public_html/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/lib/gd.thumbnail.inc.php on line 179

Warning: Division by zero in /home/silversp/public_html/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/lib/gd.thumbnail.inc.php on line 293

Warning: Division by zero in /home/silversp/public_html/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/lib/gd.thumbnail.inc.php on line 306

Warning: imagecreatetruecolor() [function.imagecreatetruecolor]: Invalid image dimensions in /home/silversp/public_html/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/lib/gd.thumbnail.inc.php on line 436

Warning: imagecopyresampled() expects parameter 1 to be resource, boolean given in /home/silversp/public_html/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/lib/gd.thumbnail.inc.php on line 940

Warning: Division by zero in /home/silversp/public_html/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/admin/edit-thumbnail.php on line 42