I'm not sure if this is intended, but after having to respawn twice in a fight against some treants and dire wolves (woodcutter quest), I went to look at a couple of the books I wrote that were on Micheal, when I opened them I found the original message in them, instead of the content that I had written a couple of days before hand.
When I went to attempt to rewrite some of the information, the original message stays as though I had wrote it, and my new message simply adds it's self right after the original. I had bought another book to write in right before noticing the changes, and first picked my pack up one by one after respawning, and then by using /c.
I have a copy of my log book on wordpad, so I'm okay there, and the other book should be easy to rewrite too, however the second bug with the original message (You can write until a number of charges...) stays in the blank books as though I wrote it. New books are unaffected.
I've also found that it affected my blank scrolls as well, making them not writable, as the content originally on them: "You can use this scroll to...", stays on them the same way the ones on the book do, and so now they're written scrolls, but have nothing I've written on them.
The title of any writable document still stays the same, though. Again, this was after respawning, and having the blank scrolls and books on person. Three scrolls, and three books. Hope that helps if it's still being looked into. =]
[After looking through the bug section more throughly, I've found that this such topic has been already posted here: http://www.escapefromunderdark.com/forums/showthread.php?t=28556&highlight=Book+problem , please feel free to delete this thread, but thank you for your time.]