I installed Windows Vista Business on my computer on February 5th and before installing most drivers, I already had it set up as a client to my Windows Server 2003 domain controller. After setting up everything on my main PC, on February 8th I set up Vista Business on a second PC and added it as a client to the same domain controller. Both of the clients were set up to load roaming profiles from the server.
While looking through my server shared folders, I noticed that the user for my main PC had not updated the user profile since I first installed Vista on February 5th. Then I checked the user profile from the user on my second PC and found that the profile had never saved on the server at all. I spent hours checking all of my settings and my Group Policy and could not find the answer. I spent hours on the web hoping that everyone was having this issue and I could not find the answer.
Finally, on some random forum someone said that the Nvidia Display Driver Service was not letting the user profile unload from the Vista computer and save onto the server. I thought it was a long shot, but I opened the services (Control Panel -> Administrative Tools -> Services) and disabled the Nvidia Display Driver Service. I reboot each of the client PCs twice and finally, the roaming user profile saved to the server.
It's hard to believe that a display driver service could cause this issue. It's bad enough that Nvidia causes the problem, but it is even worse that Windows Vista could allow the issue to occur based on a single service.