Illustrator linked files becoming unlinked/classified as a group

I am having problems with linked files in an illustrator doc, i am creating compositions that use hundreds of linked images, each image in a specified folder. When i close down the document and reopen it these images are visably preseent in the doc but are no longer classified as a linked image, when i go to the linked image panel i see the thumbnail but the root and file name are no present. Its extremely fustrating as I need to often update a linked file and locating it becomes a time consuming process.