ido-find-file fails for tramp mode

[CrazyVibes]

emacs 23.1.50.1, tramp-mode and ido mode enabled

When use C-x C-f to open /ssh:user@remote.host:/path, ido aborted
after typing /ssh: and reported:

Opending directory: no such file or directory, /ssh:

Good old find-file works. Also can use /remote.host:/path/to/file and
ido will use scp to fetch the file, even when tramp-default-method is
ssh.

Where should I look at? Thanks!