I have also been plagued with this recently and can confirm it is specific to an ad on this site (affecting me on IE and Firefox). I do not believe it is not the result of my machine(s) being infected with spyware.
My solution was to download the flashblock add-on which has solved the problem. One of the flash ads is hijacking my browsers. It appears to happen when the add area at the top or bottom displays a blank white banner. Then the next click hijacks everything.
Not sure how to best get this resolved but thought I would pass this along.
(Cacher) Lorsque vous jouez un coup dans une partie, vous pouvez décider quelle autre sera affichée en suivant en choisissant l'option appropriée dans la liste des 'aller à'. (pauloaguia) (Montrer toutes les astuces)