blank screen, after typing in my user name and password!
Try creating a new user account and login from that account. If all is ok, then your user profile is corrupt as above.
If you can login in "safe mode with networking" it points to the user account.
Other problems I've observed are with computers with Norton Internet Security, removed, but still a couple of processes running (proxy service). Normally though you will not be able to access any secure sites if this is the case.
Cheers