You are the only other person I have found with this same issue.
I was fine for 18 months and then STUCK at "signing in..." screen.
Spent 2 days with tech people and no luck -- I know the dongle is fine because it works PERFECT with my MAC and other XP machine.
I think it must be a port problem but I have tried everything on this site to delete/add etc regarding the ports.
VPN did nothing and upgrade did nothing and I even bought a power USB --electric and no luck.
So, there is now a conflict with our computer ports -- this after 1 month of questions, tech folks etc.
The answer -- HOPEFULLY, someone on here can HELP. Please!!!