From the Emerson/Lake website:
To all my friends and fans: It is with great sadness that we were forced to cancel our shows in Ohio, Pennsylvania and Connecticut.
I am pleased Keith has admitted the reasons behind the cancellation, and I trust we can leave it at that. The performance was ready; many of you heard or saw the soundcheck. Keith and I are both perfectionists. You will see that Keith has released a statement on his site explaining he felt the need to cancel because of his worry that he couldn't perform up to standard. Keith is not the first performer to have experienced stage fright, and my heart goes out to him.
This has been a difficult time and we are now moving forward with a show we both believe is technically and musically wonderful. The crew and performers rehearsed non stop through February and March. I have dedicated my life to trying to make you happy through my music and nothing saddens me more than to see that you have been disappointed by anything I was involved in. Please accept that these cancellations were entirely beyond my control and know that I am doing everything possible to ensure that these shows are rescheduled as soon as possible.
I am looking forward to seeing each of you again. I take my fans, music, and personal and professional reputation very seriously.
Thank you for all your kindness and support. Greg Lake