iTunes 7 for Windows: iTunes fails to launch with an unknown error

Symptom

After installing iTunes 7.0 for Windows, some users may be unable to open iTunes and may see the error message shown here:

The iTunes application could not be opened. An unknown error occurred (0x666D743F).

Solution

This issue may be resolved by following one or both of the options below:

Option 1

1. Click the Start button and choose Control Panel.
2. Open the QuickTime control panel and select the Audio tab.
3. In the Devices section de-select the Safe mode (waveOut only) option and click Apply.

4. 

Option 2

1. Click the Start button and choose Control Panel.
2. Open the Sounds and Audio Devices control panel.
3. Select the Volume tab.
4. Click the Advanced button under Speaker Settings.
5. On the Speaker Setup pop-up menu, click Stereo Headphones.
6. Click OK and then Click OK again.
7. Open iTunes.

Additional Information

If the Safe mode option is needed for another application, you may be able to re-enable this option once you have successfully opened iTunes 7.

This document will be updated as more information becomes available.