[Typo3] Strange problem with scaling of images

[Thomas Breuss]

Hi all

I've the following strange problem with scaling images in page content 
elements "images only", "text with image below" or "text with image to the 
right".

1) User A is scaling an uploaded image by clicking the checkbox "Width 
(pixels)" and filling in a width, per example 100. => Everything's working, 
no problem. The image is shown as thumbnail with 100px.

User B is trying the same. => Nothing happens. The image is still in it's 
original size.

2) On a computer A (at home) user B is scaling an image. => Everything's ok.

On a computer B (at work) user B is trying the same. => Nothing happens.

A few background informations:
- User A und user B are in the same usergroup with no modification of 
userrights etc.
- Access to the page and the content element is ok.
- Image Magick is properly installed.

Has anyone an idee?

Regards
Thomas