Make the timeout error message more explicit

Hello @nicks, @dpup 

Please review the following commits I made in branch 'xiao-timeout-msg'.

84633e7d44fb1bbd350313f478e14cd2924d99e0 (2014-01-27 15:34:07 -0800)
Make the timeout error message more explicity

R=@nicks
R=@dpup