There is a known problem with login going around. It is not the only login problem. However, the Firestorm-Phoenix team and Lance of Dolphin Viewer fame have provided suggestions for those using their viewers and described the problem. There are possible fixes, if your login problem is from the Viewer 3 Bug in mesh capable viewers, that’s my name for it…
A possible fix is to login with a pre-mesh capable viewer. Once your in, you can logoff and come back with a Viewer 3 version. This problem affects all viewers using SLViewer 3 code, which is all of the new Third Party Viewers with mesh render ability. I think the problem started to appear with version 2.8.something. Any viewer prior to 2.8 should be able to clear the problem.
Another suggested fix is to change your DNS service. When making a change most switch over to the Google public DNS. You can Google for instructions on how to do that on your system. A trick they do not tell you when changing your DNS service is to ping the services you are currently using and the Google services. Place the service with the fastest ping as your preferred first choice. Make the slower of Google or your current DNS the second choice. To make your system more robust use 3 or 4 DNS addresses.

