Whenever I try to play back VM from the computer to the phone it brings up a user logon prompt. I've un/re-installed, still didn't fix it. It's happening to 2 of 100 people. any guidance?

I've got viewmail installed on 50+ machines running office 2003 and VM4.2(2) and if cached exchange mode is turned on, then outlook 2k3 will hang on exit. I would turn off cached exchange, but we've got some laptop users that need that to stay on. an...