It stops working and after some time it atarts working again! but why?

if you really want an answer you will need to give more information - please check the read before you post link below.

sorry, I forgot...

XOOPS Version: 2.0.16
Module Name/Version: Protector 2.57
PHP Version: 4.3.11
MySQL Version: 4.1
Web Server Software (Apache): 1.3.34
Operating System: Linux
Theme you are using: XOOPS default
Custom template: No
PHP Debug Messages: -
MySQL Debug Messages: -
Smarty Debug Messages: -
A full description of the issue: The image manager stopped working after I downloaded a few images. After some time it starts working again. I uploaded 10 more images and then it stopped again. It looks like there are 2 specific jpeg's that make my image manager stop working. I created those 2 jpeg's by myself and the same way like all other jpeg's. There is no difference in file size, image size and a very similar file name. Following appears after I click on upload:

Could not get uploaded file 0
No file uploaded