Comment 4 for bug 483978

I seem to have the same problem.
Answer to your question: Yes, this is only when the computer boots.

When I start my computer, the Ubuntu One icon shows an exclamation mark.
After manually selecting "Connect" it connects without any problems.
When I restart Ubuntu One, it also connects automatically without any problems.

The contents of my ubuntuone-client.conf:

[ubuntuone]
connected = True
connect = 0
show_applet = 0
bookmarked = True