Yeah, i had the same problem when i first got it. I could only get the pb in when i had it perfectly parallel to the length of the bag. But after using it for about a month, carrying it to work, i can get the pb in pretty easily. It still won't fit with a sleeve though (not even close). Now that the computer gets in easier, I really like the bag. I first got a horseman, but that was WAY too big. I like the overall size of the CE. It's small enough to look like a normal bag, but big enough to fit the computer and other books easily.
Try using it a little longer. Maybe even slide the computer in when you're not using it. It may help stretch the padding.
daniel