If a PDF file prompts you with “Specify a file to extract to” DO NOT proceed. Instead press Alt-Ctrl-Del to open task manager and kill the task associated with the PDF document.

More info here...

http://blogs.zdnet.com/security/wp-mobile.php?p=6196&tag=nl.e550

Adobe's suggested work-around:
Users can also turn off this functionality in the Adobe Reader and Adobe Acrobat Preferences by selecting > Edit > Preferences > Trust Manager > PDF File Attachments and clearing (unchecking) the box “Allow opening of non-PDF file attachments with external applications”