Hyperlinks from a PDF file keep opening multiple IE windows

Hi - I wasn't sure where to start, but since the problem seem to be with
Internet Explorer, I'll start here.

I have a PDF file that contains hyperlinks to URLs. When the link is clicked
in the PDF file, they take me to the correct website, but two tabs to the
same web page open, along with another separate IE window that doesn't show
anything - it just appears to be connecting.

Has anyone encountered this before? Any suggestions on how to stop this from
happening? I am using Internet Explorer 7.

Thanks!