ATTENTION NEW SECOND LIFE USERS!
If you downloaded the "official" Linden Lab viewer as part of your signup process, and you are crashing, please either uninstall that viewer and re-download the LL viewer, or download and install one of the Third Party viewers such as Firestorm
The problem viewer is version 3.5.2, and you can see what version you are using by going to the Help/About Second Life menu item at the login screen.
The crashes are occurring on Windows Vista, Windows 7, and Windows 8, and ONLY affect new Second Life users.
LL removed 3.5.2 from their download page, and put back version 3.5.1. It should be stable.