A friend send me a hint and I found something in a google forum - after deleting cookies, cache and browser history in chrome no warning anymore when I search 'marco tozzi'.
Some people think that it has to do with the 'google picture' search... I did use the picture search before the warning on the web search site popped up.
I'll give GooredFix a try when I have time (maybe this weekend) - hope I'll never have this problem with FF.
And last but not least a little praise for Avast - I really like it that Avast warns you and blocks the bad things