I've been using Outlook.com for a few months and have problems with calendar items disappearing (events scheduled in the future).  I primarily use Outlook 2013 on a Windows 8 desktop to create events.  I view the events using this Outlook client, web browser, and iPad.  I often have events disappear from my account.  I've had them disappear within a day or several days after being created.  They do not show up in deleted items, and I see no way they are being deleted.  I can provide specific examples for troubleshooting if there is someone at Microsoft who can help.