I have a personal account that I use at Outlook.com along with some other accounts that connect via Exchange. So I use Outlook 2010 for my main email program. Every so often, though I would get the error 0x80048051 when checking my email and no email from Outlook.com would show up.
The solution involves Microsoft Internet Explorer. For some reason, this program will self select the File / Work Offline toggle. When this happens, Outlook is unable to connect to my Live/Outlook.com email. Very strange as I don’t generally use IE and how this setting get’s changed seems quite strange. Still, an easy remedy. Whenever I’m unable to sync my Live/Outlook.com mail account, I simply open IE and deselect Work Offline (under the “File” menu).
Credit for this solution goes to the thread here:
Hope it helps! 😉