Thomas,
The image is generated automatically, because the Post image on error setting is enabled in your project properties. To get only one picture in the log, disable this setting and use Log.Picture within the OnLogError event handler.
To find the setting, right-click your project in the Project Explorer, choose Edit | Properties from the context menu. This will open the project editor and activate its Properties page. On the page, select the Playback category from the tree on the left. The setting will be on the right, at the bottom.
