架构游戏引擎node时遇到问题

就是 npm install grunt-cli -g时出现如下错误:

33 error Error: CERT_NOT_YET_VALID
33 error at SecurePair.<anonymous> (tls.js:1367:32)
33 error at SecurePair.emit (events.js:92:17)
33 error at SecurePair.maybeInitFinished (tls.js:979:10)
33 error at CleartextStream.read [as _read] (tls.js:471:13)
33 error at CleartextStream.Readable.read (_stream_readable.js:340:10)
33 error at EncryptedStream.write [as _write] (tls.js:368:25)
33 error at doWrite (_stream_writable.js:225:10)
33 error at writeOrBuffer (_stream_writable.js:215:5)
33 error at EncryptedStream.Writable.write (_stream_writable.js:182:11)
33 error at write (_stream_readable.js:601:24)
33 error at flow (_stream_readable.js:610:7)
33 error at Socket.pipeOnReadable (_stream_readable.js:642:5)
34 error If you need help, you may report this *entire* log,
34 error including the npm and node versions, at:
34 error <http://github.com/npm/npm/issues>
35 error System Darwin 13.4.0
36 error command "node" "/usr/local/bin/npm" "install" "grunt-cli" "-g"
37 error cwd /Applications/MAMP/htdocs/gorescript-master
38 error node -v v0.10.30
39 error npm -v 1.4.21

然后终端不认grunt命令!