石橋を叩いて渡る

Excite翻訳: It wears a belt and braces.
@nifty翻訳: It is overcautious.
Babel Fish: Hitting Ishibashi, it crosses
Google翻訳: Hit the stone bridge across
Yahoo!翻訳: I knock on the stone bridge and pass
OCN翻訳: I hit a stone bridge and cross.
Windows Live Translator: Beating the Ishibashi cross.

Summary:
It seems that Excite's is registered in its dictionary as a fixed translation though I am not sure whether the meanings are the same between English and Japanese.
@nifty shows the correct meaning.

Reverse Translation)
Excite翻訳: それは石橋を叩いて渡ります。
@nifty翻訳: それは用心し過ぎます。
Babel Fish: Ishibashiに当って、それは交差する
Google翻訳: 造りの橋を渡ってヒット
Yahoo!翻訳: 私は石橋をたたいて、通ります
OCN翻訳: 私は石橋と十字を打ちます。
Windows Live Translator: クロス石橋をたたいてください。

Summary:
@nifty's is a normal expression which has the same meaning as the original expression.
It appears that Excite and Yahoo! succeed to reproduce the original Japanese though they do not the real meaning.