npm installしようとしたらエラーでた

Node Express

dotinstallのExpressをやろうとしてうまくいかなかったので

http://dotinstall.com/lessons/basic_expressjs/26502

$ cd sample && npm install
npm http GET https://registry.npmjs.org/jade
npm http GET https://registry.npmjs.org/express/3.0.0beta7
npm ERR! Error: SSL Error: CERT_UNTRUSTED
npm ERR! at ClientRequest. (/usr/local/lib/node_modules/npm/node_modules/request/main.js:409:26)
npm ERR! at ClientRequest.g (events.js:185:14)
npm ERR! at ClientRequest.EventEmitter.emit (events.js:88:17)
npm ERR! at HTTPParser.parserOnIncomingClient [as onIncoming] (http.js:1445:7)
npm ERR! at HTTPParser.parserOnHeadersComplete [as onHeadersComplete] (http.js:111:23)
npm ERR! at CleartextStream.socketOnData [as ondata] (http.js:1356:20)
npm ERR! at CleartextStream.CryptoStream._push (tls.js:396:27)
npm ERR! at SecurePair.cycle (tls.js:751:20)
npm ERR! at EncryptedStream.CryptoStream.write (tls.js:131:13)
npm ERR! at Socket.ondata (stream.js:38:26)
npm ERR! [Error: SSL Error: CERT_UNTRUSTED]
npm ERR! You may report this log at:
npm ERR! http://github.com/isaacs/npm/issues
npm ERR! or email it to:
npm ERR!

npm ERR! System Darwin 12.3.0
npm ERR! command "/usr/local/bin/node" "/usr/local/bin/npm" "install"
npm ERR! cwd /usr/local/bin/sample/sample
npm ERR! node -v v0.8.0
npm ERR! npm -v 1.1.32
npm ERR! message SSL Error: CERT_UNTRUSTED
npm ERR!
npm ERR! Additional logging details can be found in:
npm ERR! /usr/local/bin/sample/sample/npm-debug.log
npm ERR! not ok code 0


=>
$npm config set ca ""
これで解決