Apple released an update to their Keynote presentation software yesterday evening, bringing the version up to 5.1.1 and improving how the app handles large documents.
In addition to the document handling fix, the update also includes several other minor improvements, and is recommended for all users of Keynote 5.1.
As Apple notes in a related support document, users who installed Keynote outside of the Mac App Store should update through Software Update, whereas those who purchased Keynote from the Mac App Store should update through that channel.
Apple also released a minor update for iCloud Control Panel for Windows, bringing the version up to 1.0.1. The update is required for Windows PC owners to setup Photo Stream, as well as for syncing Contacts, Calendars, and Bookmarks data with their iOS devices.