As with anything, keeping 10+ years of information of anything, without making a backup of any sort, and keeping this on your mobile device, has disaster written all over it. While there have been memory issues in the past, the newer BlackBerry devices are coming with more internal memory, more than enough to handle calendars, to do lists, apps, etc. One way to ensure that you don't lose important stuff, is to delete stuff that you don't need, like call logs, text messages, junk mail, etc. It is just like a computer, you don't keep unnecessary junk on it, so why would you on your phone?