I have downloaded my audio books several times in the last couple of weeks and every time i close itunes they get removed and i have to download again. it is getting very ridiculous and is very upsetting. can someone help?

Do you have any third party security software? If you check for hidden files in the main iTunes folder do you see a bunch of .tmp files? I suspect the updated library isn't saving properly. Have you looked inside the folders where these books download to in order to check for duplicate files and local copies that you could add to the library instead of redownloading?

tt2