in C:\Program Files (x86)\Steam\config there are no: \overlayhtmlcache\ \htmlcache\
i closed steam deleted appcache\httpcache\ and restarted steam.
still getting the ads in the browser and the javascript popup
Alright, i found out what the adware that infected my system is called: "Hades Adware". I removed it with the guide on malewaretips. thanks for the help tho. you can close this thread now