Sorry for the delay in response.
Could you please elaborate on your query? Does Internet Explorer stuck when viewing pdf files in the application?
Where are the pdf files located- on a network location?
What is the complete version of Internet Explorer installed on the machine: https://support.microsoft.com/en-in/help/17295/windows-internet-explorer-which-version
And, the application- Reader/ Acrobat installed on the machine?
You may refer to troubleshooting steps given in this link: Troubleshoot viewing PDF files on the web
Awaiting your response.