Save it to disk and attempt to open it with a different program that could "save as" in a different format or convert the file directly.
Is it in .lit format? I am not too good at reading the traceback but there are several applications out there that can convert a .lit book.
Here is one of them and it is free:
http://www.convertlit.com/download.php
If it still bombs on conversion it may not actually be a .lit file. Someone may have put the wrong extension on the file. I have quite a few .rtf's that are actually .txt's and once the extension is changed they open just fine.
Good Luck and Happy Monday