ibooks won't open new epub or pdf files

I have seen this subject discussed at length but have found no clear solution in existing discussions so thought I'd revive the topic in a hope of finding a solution.

To recap the problem, whenever I try to open a new file in iBooks today, one of two things happen:

1. iBooks looks like it is trying to open it for a few seconds and then stops. file does not open.

2. file opens for like 1 second and disappears.

As you can imagine, this is extremely frustrating. One of the main reasons why I bought the new iPad was because the screen was gorgeous. And the 10 inch format meant that reading PDF files was very enjoyable, especially with the single tap to increase the size of fonts to fit the screen size. Epub files were equally enjoyable to read, esp since Kindle can't handle them (why is that?).

But now, I have a legacy library (which is good) but no ability to open any new pdf or epub, which is horribly frustrating. I have resorted to opening them in iAnnotate (does not scroll downwards smoothly), Goodreader (not as good a user interface), filebrowser (also not a great interface, cant open epub files), dropbox (same problem).

And why isn't Apple doing anything about this with an upgrade fix?? While I've always loved Apple product, it does feel like Apple is taking its customer base for granted to some degree - problems like this with multiple complaints over so many months have received no response. Apple has the best tablet for now but the gap will close as surely as it did for the smartphone.

If anyone can help me solve this thorny issue, I will be eternally grateful.