I have used Adobe Reader XI, both version 11.0.0 and 11.0.2. Both gave me problems reading a pdf file created with another software program. In short, I could not search or find anything in the document, even though I know there was a text layer there. I could do the search in pdf files I downloaded from the Internet. I could not even PageUp and PageDown, or move to another page (other than page 1) using the page box at the top. Eventually I went back to using AR X, and the problems disappeared.
This post is about using AR XI for reading pdf files that I downloaded from the Internet. Therefore, this is not a file specific problem. When I opened AR XI and went to the Help menu > About Acrobat Reader XI a window popped up with the proper information. Clicking on that window should close it, but it would not close. Clicking the x in the box on the upper right did not close the program. I had to use Windows Program Manager to unload the program.
My computer is about a year old and runs Windows 7, X-64.