[Plugin: NextGEN Gallery] adding images – create new thumbnails causes error

i’m using 2.8.4 and ngg 1.3.5. everything has always worked fine until now.

i’m trying to create a new gallery by using the “import image folder” option. there are some 93 images in the folder. about a third of the way through, i start getting a repeating error:

ID 1275: A Failure occured
[more]
[objectXMLHttpRequest]

it seems to be related to the number of images, i tried doing about 30 and it worked. as soon as i added more images i get this error, whether directly through “import image folder” or by having ngg scan for new images in the folder.

please advise