I want to report a strange bug and i need your help.

I have an installation with the following features:

Drupal: 6.25
PHP: 5.3.21
Web server: LiteSpeed
File system: Writable - Public download method

cck 6.x-2.9
FileField 6.x-3.11
ImageField 6.x-3.11
Insert 6.x-1.1
FileField Paths 6.x-1.5
FileField Sources 6.x-1.4

Web browser:
Firefox 22.0
Internet Explorer 10

I have an image field with unlimited number of images, everything works well until the 15th image, the 16th image is uploading ( to /public_html/sites/default/files ) but not saved in the node.
When you reopen the node the 16th image ( and over ) does not exist.
The button "add another item" is working, and you can create unlimited image uploaders but from 16 and over the images will not saved.
The images is still on the folder /public_html/sites/default/files but not in the node.
One more thing, when you upload the 16th image and push the button "add another item" create a new uploader but the 16th image disappears.

Thank you