Spinal Tap has nothing on this. Via RW70, aka Rob Warmowski:

So what happens when you’re Van Halen, the last song in your set list is the million-seller “Jump” with its synthesizer-keyboard opening…and the recording you’re using to play back the synth is accidentally run at 48K instead of 44.1K?

What happens is exactly this (recorded in Greensboro, NC four days ago)

Yes, just as disturbing as the possibility that your backing tracks could spontaneously introduce a new tuning system in front of thousands of fans, hundreds of thousands more may know about it within days on YouTube. Techs everywhere just felt a chill go up their spine. Erm, once they stopped crying they were laughing so hard.

If you enjoyed this musical performance, get ready for Guitar Hero IV: Quartertone! Charles Ives Expansion Pack!

And Van Halen, the American Festival of Microtonal Music here in New York may be able to welcome you soon.