Thanks a lot, folks. I went for Sumatra. It works like a charm. It can even keep more than one pdf output in tabs.
Only thing: when I close the Lyx file I was working on, without closing Sumatra, I get a message saying something like "Couldn't close temporary directory". Something similar comes even when I exit from Lyx. I hope it's harmless. Ashok PS: A bonus for using Sumatra. It makes viewing other ebook formats easy to read. Unlike Calibre, it doesn't insist on bringing ePub or Mobi into its library first. It reads it. What's more: it's a very good .chm reader! I'm thinking of making Sumatra the default viewer for pdf and everything; keeping Acrobat Pro only for those occasions when I want to edit or combine pdf files.