Lutz,
I've checked your account and you have 10 attachments across the forums, many of which are very large (600Kb - 1Mb) and this is what has caused the system to prevent you from posting more. I would strongly recommend that you look at each post and reduce the size of the images on there (in both pixel size as well as file size).
Here are a list of your largest attachments:
Let me know if you need further help in reducing the size of your attachments.
Cheers!
