Can't open PDFs using IE 10

I can still open PDFs I receive as an e-mail attachment.  But suddenly I can no longer open PDFs using IE 10, such as those I find links to after a Google search.  I am using Reader 11.0.02 and IE 10.0.9200.165400.  The failed attempts result in a blank white page with a small box with an "x" inside in the extreme upper left of the blank page.  I've tried Google search troubleshooting.  Made sure that the IE add-on for PDFs was enabled.  Any ideas, other than downloading Firefox?