 The head of the Secret Service, Kim Cheadle, will appear before Congress today. House Oversight Committee Chair James Comer issued a subpoena to ensure that she will be there. A bipartisan independent review of the attempted assassination of Donald Trump will also take place. Residual problems for some businesses following last week's CrowdStrike software update failed. Delta Airlines has been one of the hardest hit. They had to cancel over a thousand flights on Sunday. Hundreds more already canceled today. You're listening to ABC News.