Today I purchased a highly recommended e-book ('Rally All Around') which is available by download. Double clicking on its file brought up a message that I needed a newer version of Adobe Reader, and linked me directly to 11.0.06 (Mac) on the Adobe site, which I downloaded and installed. Unfortunately, this application refuses to launch: irrespective of whether I try to launch it directly, from the Applications Folder, or by double clicking the new book, I receive the 'An internal error occurred' error message and the program shuts down. I have followed the advice provided in this forum for a previous version of Reader: I deleted all existing versions of the program, as well as the Adobe Folder in my Library, then attempted to reinstall. I've also used 'Get Info' to ensure I have the required read/write permissions on the application, and the Adobe Library Folder. Unfortunately now I have lost the ability to open any PDF file at all! I'm very unimpressed (to say the least!) that I have lost hours trying to troubleshoot this problem, as well as my money for the book and functionality on my machine! I am running Mac OS X 10.9.1 on an Intel Core i5. I'd be grateful for help, and advice, if you care to share. I'd like to count to 10 and try and fix this, before succumbing to the temptation to send a howler to the publisher.