SLIPKNOT has released the following statement:

"We're sorry to announce that our brother Jim Root [guitar] will not be performing with us at [Rockstar Energy Drink] Mayhem [Festival] today in San Bernardino due to serious health issues. Jim has been seriously sick for the past two weeks and went to the hospital last week where he was advised that his appendix burst a couple weeks before and that it could have been life-threatening. Jim is at home recovering and is awaiting surgery to have pieces of his appendix removed and hopes to join the tour as soon as he is able. SLIPKNOT will continue to headline the Mayhem festival and all other shows. We refuse to let our fans down and will not miss a single date. We will miss Jim greatly and our thoughts are with him. Jim sends his love to each and every one of our fans."

SLIPKNOT began its return last summer with a European tour, continued it earlier this year with jaunts through Australia and South America, and will now complete it this summer with a headlining slot on the Rockstar Energy Drink Mayhem Festival. The icing on the cake will be Knotfest, two festival dates put together by the band itself on August 17 in Council Bluffs, Iowa and August 18 in Somerset, Wisconsin.

In addition to the headliners, both days will include sets from DEFTONES, LAMB OF GOD, DETHKLOK, SERJ TANKIAN and PRONG.

Also playing at the Iowa show will be THE URGE and DIRTFEDD, while the Wisconsin show will also feature CANNIBAL CORPSE, GOJIRA and THE DILLINGER ESCAPE PLAN.

Knotfest is being positioned as a "dark carnival experience," and the event will feature circus tents, pillars of fire, amusement park rides, burlesque performers, fire-breathers, stilt walkers, drum circles made of junkyard cars, graffiti walls and even a SLIPKNOT museum.

The festival will mark the end of a two-year grieving period for the band following the May 2010 death of bassist Paul Gray from an overdose of drugs.

SLIPKNOT will tentatively enter the studio sometime in early 2013 to begin recording its fifth album. In the meantime, a greatest hits collection called "Antennas To Hell" arrives on July 24.

SLIPKNOT will also release its first-ever mobile app, Wear The Mask. The app will be made available simultaneously with "Antennas To Hell" and is marketed as part mask builder, part social connector for fans.