Opening a PDF file will take you to a busy icon for a few seconds and then does nothing. It is even more bizarre as Adobe Reader or Acrobat does not show any error ...

Adobe Acrobat Reader DC software is the free, trusted standard for viewing, printing, signing, and annotating PDFs. Its the only PDF viewer that can open and interact with all types of PDF content ...

Added by Adobe Acrobat Reader Standard 9.0 ... Files\ or C:\Program Files (X86)\ depending on whether the version of Windows or the program being installed is 32-bit or 64-bit.