Some images won't show on the website, there are a few images that show with a red cross. I have tried to pre-cache but that did not do the trick.
Most pictures are ok, does anybody had the same issue?

Please read here: http://www.zenphoto.org/2007/12/troubleshooting-zenphoto/#11

The pictures I'm using are not bigger then 800KB, how is this possible?

The dimensions are the important part, not the actual file size. What width and height do your pictures have?

Thank you for your feedback acrylian.
Where can I find the actual size width and height.

I suggest using your image editor to take a look. Some systems also show the dimensions of the image (Mac OS X does, I am sure Windows does too).

One of the images with problems has a Width:2592 and a height:3872

I have 50 pictures taken with a 8.1 MP camera, this means 2GB or more memory use.
With my provider I have 250 MB webspace. Could this be the problem?

The webspace has not much to do with the server limit for processing images and other things. Just make your images smaller before uploading.

EDit: Sorry it solved I just add to uncheck the enable mod_rewrite box. Sorry I should have read more

Hello there, I have the same problem, and don't know what to do sorry I'm really new to this.

Basically I manage to upload my pictures which are all 800533 or 533800 resolution pics with a weight around 150Ko I can see my album being created in the 'albums' folder of zenphoto however in the admin tools I cant see them and when I'm looking at the gallery, the album is created with a red cross in place of the thumb and when I click on the album I got an error 404: object not found ...

Any hints ?