YouTube videos appear to begin loading but very quickly stop after one or two seconds, and a message stating 'An error has occurred. Click here for further information' is displayed.
Videos play normally in other browsers, such as Chrome or Firefox, when going through the same proxy.
The cause of the problem is that Internet Explorer is detecting there's no usable audio playback device on the host PC. The most obvious visual indications of this condition will be the audio error symbol in the Windows notification area (system-tray), or that all of the Playback devices listed on the Playback tab in the Control Panel sound applet are greyed out:
It should of course also be obvious that no sound is audible through the PC's speakers or headphones, if either of these are connected.
To fix the issue, any configuration problems with the audio playback device on the PC should be corrected, or if the playback device is disabled it should be re-enabled.
If no audio hardware is actually installed on the PC, possible solutions would be either to install suitable audio hardware (e.g. an internal or external sound card), or if this option isn't practical, to install a suitable audio-hardware emulation software program and driver.
Although Symantec cannot provide any recommendation for a specific vendor of such hardware or software, lab' testing has shown that e2eSoft's VSC software is effective in resolving this issue when correctly installed and configured.
Since this issue is known to occur with or without a proxy present, the solution above is provided on an as·is basis, and no guarantee can be given for its effectiveness in every situation.