I'm having the exact same problem. U1 worked beautifully for the last two years across my linux (11.10, 12.04) and windows (XP, 7) computers. The client asked to upgrade (I think it installed version 4) and the whole thing ground to a halt. Just as described, it hangs at "File sync starting" from the system tray. If I open the client, it always says, "gathering information." Rolling back to the previous version I had that worked (2.3) until this issue gets properly addressed.
Hi, that's interesting. It could be that version 4.0.0 for Win7 is having this issue. Where I could download from an older version of Ubuntu One for Win7?