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Many thanks Chuck and Trish. You've both led me to 'Foxit reader' which I now have installed and working. I uninstalled Adobe Reader, which I think was the problem (it remains to be seen what happens when I switch on tomorrow!!), but still have on board Adobe Acrobat, AIR, Flash Player and Shockwave. I don't know whether they are still necessary with Foxit so will have to do a bit more experimenting. I wonder if Foxit will do just as well withoujt them?