Everything done!
Only one glitch - I couldn't follow your instructions to delete combofix. I tried right clicking on it and chose delete programme. I hope that is all ok.
The PDF thing scared me a bit - I'm forever downloading PDFs of journal articles for my research. I have made a note of your instructions for that (and everything else) so that I can keep my computer updated.
The good news is that I haven't been redirected from google over the last 24 hours so hopefully your magic tricks have worked ;-)