The problem may be in your computer. Some users have reported that opening PDF files makes their computer freeze after long periods of being able to use the PDF files in the past. The Adobe site offers a help file for just this problem and it can be accessed at ADOBE.
This problem is not a site problem but a problem within your local computer and it needs to be corrected by you. We can not change settings on the site to correct the problem for you. The Adobe site is your best resource for this particular problem.