The Register reports the LHC was briefly knocked out this morning by a power failure. Fortunately the issue did not cause any heating to the magnets, otherwise the LHC could have been out of operation for a couple of days.
It appears that a failure occurred at 01:23 Swiss time this morning in an 18,000-volt power line at the Meyrin site above the mighty collider's subterranean circuit. This caused a power cut across the site, shutting down the main computer centre among other things and causing an abrupt cessation of operations.
However according to CERN controllers and the publicly-viewable web readouts (now back online) the LHC's magnets stayed chilled down to their operating temperature, just 1.9 degrees above absolute zero - colder than deep space. This is critical, as re-chilling the magnets had they warmed beyond a certain point would have been a lengthy and involved process.