What's going on is no disorder or anything. It's simply a lack of focus. Here's an example.
I'm reading an A+ book too. However, since I know most of what's in it, I'm skimming what I know and reading word-for-word what I don't. Some of it is interesting, MOST IS NOT. The way textbooks and reference books are written is very to-the-point and dry. Now, I have a great book that tells why your brain doesn't learn that, and that would be "Head First: Java". Java isn't a fun subject to learn by reading. I read 20 pages of Sun's Online Tutorial and learned NOTHING. The first chapter of Head First: Java explains why.
Your brain doesn't take to things it thinks aren't important. You may think it's important, and really want to learn it, but your brain thinks differently. If you had to fight a tiger, your brain would remember what you did. If you read a chapter in your A+ book, your brain would leave the space for something more important. Head First: Java counters this by making things fun, interesting, and giving stories for examples that help things stick. Since the A+ book doesn't, it just means you'll need to reread, do the quizes at the end of the chapters, and reread again. Simple as that. My suggestion is read before you go to sleep; science has proven this to help you remember better. It's what I'm doing with both books, and trust me, it works.