Have had this problem for awhile and haven't upgraded NextGen because of it - but just found an answer on another post.
Basically, create a file named imagebrowser-caption.php, copy the contents of imagebrowser.php to it and save. Then upload or ftp to the "view" folder in the nextGen plugin (...wp-content/plugins/nextgen-gallery/view/imagebrowser-caption.php). If you have cpanel you can just create a new file, name it, copy the contents and save.
I just tried and it worked for me.