the day. meanwhile, united airlines hoping to be back at full speed this morning after a computer problem grounded more than 800 flights yesterday. big problem. it affected tens of thousands of passengers across the country from chicago to denver to l.a. nbc's tom costello has more on the latest problem for the second largest airline in the united states. >> reporter: it all started just after 8:00 a.m. eastern. united says a computer router failed taking off flight scheduling and passenger check in systems. that led to an faa ground stop for all united flights nationwide until 10:00 a.m. got news it happened on wednesday, one of slowest travel days of the week. the bad news it's the height of the summer vacation season. >> it's always frustrating when there is a delay. we have our vacation planned and travel and stuff like that. >> in all, more than 800 flight delays roughly 60 united and united express flights canceled. just the latest disruption cause bid computer glitches since united merged with continental in 2010. the most recent on june 2nd