Occasionally, when opening PDF files off of websites through Internet Explorer, Adobe Acrobat will freeze up and temporarily stop or slow Internet Explorer from working properly. This problem also has the tendency to freeze up a computer all together.
I have personally encountered this problem on Windows XP numerous times, and may have caught it on Vista once or twice.
If your computer freezes after opening an adobe PDF from Internet Explorer, open the Task Manager by holding ctrl+shift+esc simultaneously.
In the task manager, find the file listed as Acrord32.exe and left-click once to highlight it. Once highlighted, click the “End Process” button. After clicking the “End Process” button, a warning window will open, click “yes”.
This solution should work if your system is frozen because of opening an Adobe Acrobat PDF file in XP or Vista. After unfreezing your system, I would recommend saving any files you are working on, and restarting your system.