Can't boot into Ventura volume
I'm on a 2019 MacBook Pro. It has two internal volumes, one with the current version of Sonoma and the other with the current version of Ventura. I can suddenly no longer boot into the Ventura volume. It was working a few days ago. Ventura is set as the boot drive. When I start to boot it, the goes through the process, the white bar gets to the end and stalls but the system never opens. I went into Sonoma and ran Disk Utility First Aid on the volume and its two components. It said it was OK. I can even boot into Monterey on an external drive, though start up does seem unusually slow.
Does anyone have any suggestion how how I can get the Ventura volume going again?
Thanks very much.