Hello John,

thanks for the fast response.

I have deleted an old sitemap component which I used until I purchased Jsitemap.

I also checked the virtuemart plugin you mention, but this didnt exist in the plugins of our website.
At last, I checked the list of buggy plugins you mentioned, but I had noone of them.

Tried resubmit the xml sitemap in google, but still same error.
Then I thought this may be a google cache issue in webmaster tools. I deleted the sitemap, resubmited, but again, same issue.