Did the leaves fall off? Something not working right? Let us know how we can improve the Photosynth experience.
I've been trying to log on all day now and I get stuck at the "signing up" stage. after a few minutes I get a humorous message as follows: "Did you hear that? That's the sound of us banging on our authentication servers, which currently aren't working. Please try again later". I haven't seen anyone else complaining about this issue, so I recon it's only on my PC. System specs: Windows XP 64 bit, 8GB RAM, CPU Q6600, 2 Disks in RAID0
What browser are you using and is it a 64bit browser?
I've had this problem. What I did was click on the file "PhotosynthInstall.exe" and hit repair. See if this works for you.