Happening to me as well. Let me know what you find out from VZW.
I'll jump on the list here. I'm having the same problem. Keeps prompting for password. I even reset my pw this morn. I put in what I know is right pw. Always tells me invalid pw. Calling vm directly and punching in pw works fine. VVM just doesn't accept pw. Just started today.
I then got busy at work and around 1:30pm left the office for an errand and as I was exiting the city almost at the same spot where I lost use of the app in the morning I heard the tone for my vvm. I typed my same password in (for like the 20th time that day ) and I was back in business. Not sure if it was self cured, maybe something going on with that tower or VZW did something but it's been working flawlessly since then including yesterday afternoon and this morning when I'm back in the city.