When downloading .mp3 files using Internet Explorer or any other browser, the Save As dialog may add an incorrect file extension (.mp2 or .mpeg, instead of .mp3). Whenever this happens, you need to manually change the file extension to .mp3.
If this problem happens when downloading .mp3 files from a particular website, then it’s possible that the web server is sending a wrong MIME type for .mp3 (Default MIME settings for IIS.) With that said, it’s a server-side setting that needs to be fixed by the administrator.
On the other hand, if this issue occurs for every website, the Content Type registry setting in your system might be incorrect.
Instructions for Windows XP
1. Click Start, Set Program Access and Defaults
2. Click Custom to expand the section
3. Under Choose a default media player, select Windows Media Player
4. Click OK.
Instructions for Windows Vista
1. Click Start, Default Programs
2. Click Set program access and defaults
3. Click Continue when you see the User Account Control (UAC) prompt.
4. Click Custom to expand the section
5. Under Choose a default media player, select Windows Media Player
6. Click OK.
This not only sets Windows Media Player as the default player for media files in the system, but also fixes incorrect MIME settings for many file types automatically.
Download mp3_mime_fix.zip and save to Desktop. Unzip the archive, and run the file mp3_mime_fix.reg. Click Yes when asked for confirmation. This .REG file fixes the settings under the following registry branches: