save background/reference image

I am using 2.57b. I can load background images however I can’t not save them. When I reopen the file only changes to the model are visible. The usual Cntrl S or Cntrl W don’t seem to work.
Thanks

Did you move the background image file from it’s original location?
You can pack the background image file with the .blend, so that you can carry the .blend anywhere and still have the background image file.
Where you load the background image, in the source part, there is a button left of the source file address. If you hover your mouse over it says “Pack an image as…”. Press it and the image is joined to the .blend file. Like if they really love each other.

Thanks, That was the part that was causing the problem.

Np, glad to help