wordpress creates 404 non existent pages building up in google tools

Im getting 404 pages on a regular basis building up in my google webmaster tools, these pages are not found in my website or sitemap but seem to be created on there own outside of my site.

they were also appearing in seo ultimate plugin then i added another plugin named 404 to start,, this resulted in the stopping of 404 pages building up in seo ultimate.

but to this day these nasty things are building up in google tools.
and when i run the site in some seo tools looking for broken bad pages they dont exists.. thanks for reading please help