http://docs.info.apple.com/article.html?artnum=300832

Mac OS X: No audio from certain multimedia content
Some audio applications may change your computer's audio settings to a sample rate that is too high for other applications to use. In this situation, system alert sounds still work, and does iTunes, but other applications may have no sound (audio output). This document applies to Mac OS X 10.3 or later and applications that use QuickTime 6 or later for audio, such as Safari and Quicktime Player.

This can happen on Macs that support high sample rates (higher than 48000 Hz):

iMac G5
Mac mini (all models)
Power Mac G5 models that support sample rates higher than 48000 Hz
PowerBook G4 support sample rates higher than 48000 Hz
MacBook
MacBook Pro
iMac (Early 2006) and later
Mac Pro


For example, if you play an Internet movie in Safari, it will make no sound; if you open a QuickTime movie on your computer, QuickTime Player reports the following error (and the movie will have no audio):

"You may experience problems playing a sound track in (Movie Name).mov because a software component needed by the movie could not be opened."

Solution

Open Audio MIDI Setup (/Applications/Utilities/), then check the Audio Output setting.
Change the Audio Output setting to 44100.0 Hz.
Quit Audio MIDI Setup.


Why does this happen?

Some third-party audio applications may change your computer's audio output setting. In fact, if you use the third-party application again after applying the above solution, the issue might occur again. Observe changes by watching the settings in Audio MIDI Setup before and after running a third-party application you suspect might be causing the issue. Contact the manufacturer of the application for more information.

Related Terms: mute muted mutes muting streaming stream streams streamed

各位大大請幫幫忙阿！
之前就有很多人問過相同的問題,可是都沒人解決
希望這次可以幫忙一下
別讓這個問題又沈下去了！
謝謝！

我幫你推推  我的也跟你一項出問題了
請知道的人幫幫忙吧ｘｄ   一樣重灌real了還是不行

謝謝 不過小弟我不是這個問題【沒有裝】 
不過後來倒是莫名其妙的好了  拿一堆影片avi mpeg 用其他的開開   最後神奇的是發生了
real player 自己好了  不知道是不是我有一陣子沒開real的關係xd

有保固嗎？