I'm using Firefox 4.0.1 on Windows 7 Home Premium 64-bit. I set up a sync account to transfer my history, etc. from my old desktop to my new laptop (details above). Since then, i haven't used my desktop, just the laptop. For about the last week or so, the following error message keeps popping up at the foot of the screen: "Sync encountered an error while synchronising: Unknown error. Sync will automatically retry this action." And there is a 'Sync now' button. I can't think of anything that I've done (installing extensions, etc.) to cause this to happen. Any ideas, anyone? All help appreciated.