Thank you! I will contact my theme author and see if they can help me.
Soeren
OK, I have activated NextGEN Gallery again. Please have another look at my website http://www.gemofchina.org
Now the galleries work but the slider on the home page only shows one picture.
Yes, there was malware on my computer that got installed when I installed another software today. I removed it just now and the spam link also disappeared.
Thanks for responding so quickly!