Sometimes there are problems viewing large PDFs in Adobe Reader. PDF documents can take a while to open and when scrolling, Adobe Reader can freeze and, occasionally close down altogether.  The behavior is not consistent but if you encounter it with a file you're using, the following suggestions will help you to view the page more easily.
 
1. Disable protected mode on startup
 
Click on Edit > Preferences and then in the left-hand pane select the General option (in Acrobat Reader X) or the Security (enhanced) option (in Acrobat Reader XI) and untick the option "Enable Protected Mode at startup" then click OK
 
This reduces the time it takes for Adobe to launch and should address problems with the application appearing to "freeze" when you first open it, but if you still have problems, try:
 
2. Disable the page preview on the scrollbar.
 
Click on View > Page Display > Enable scrolling 
 
This turns off the little page preview which appears next to the scroll bar if you scroll through the document by clicking and dragging. This preview can cause a noticeable lag, especially if you drag a long distance.

And, if you have not already done so, Try saving the file locally on the computer you are using. Sometimes network delays can be the cause of a slow response so if you want to be able to go backward and forwards through a file quickly.