I can build my iPhoto book book but it will not upload. It hangs up and asks me to retry. endless loop.

Five Steps to a Great Book / Cards / Calendars - http://support.apple.com/kb/HT2536.

How To Preview a Book / Card / Calendar Order - http://support.apple.com/kb/HT1040.

First preview the book to ensure that all the pictures appear fine in the preview.

What is the exact error you are getting, as this may help determine what you need to do for a resolution.

Also, try to connect to the internet direct wire instead of wireless for best results.

Boot into Safe Modeand try again.

That didn't work for me. First I had to delete the com.apple.iphoto.plist, then re-install iPhoto, then boot in Safe Mode then it worked. What an epic.