Vielen Dank für Ihre Antwort schrauber
(my German is rusty, haven't practiced in years)
No worries about the late reply; I know that everyone here is a volunteer working during his free time and that you get overwhelmed by the topics asking for help
as for my issue, i was able to solve it; i will post the details so everyone consulting this thread and having a similar issue would have something to build upon.
Shortly after starting to have this annoying pop up at startup from SAV (Trojan.webkit!html),
I noticed a strange behavior from my sidebar:
all the gadgets were loading immediately at startup except for one that was taking longer to load; it was the "weather bug" gadget (which was working fine since the day i added it to the sidebar some 2 years ago)
I knew that my system was clean and i was suspecting a false positive (refer to my earlier post - link above). I uninstalled this gadget and .... no more pop ups from SAV
just to be on the safe side, i disabled system restore, rebooted in safe mode, ran SAV, malwarebytes, superantispyware, spybot, windows defender...
ran ATF to clean any junk files in temp folders
restarted several times, all is ok
installed a better weather gadget from "weather channel-weather.com"
so far, all is well
hope this will be of help for anyone with a similar issue
thanks again for your time