Try the VLC player for these files;

That Windows Media Player 11 error code C00D1199 is common, but there is not always a single answer. It may be a CoDec problem, or something else. The VLC player has it's own codecs and can usually play most files.

Just one thing though about email attachments. It is not a good idea to play attachments directly from the email software as your anti-virus might not get a chance to scan it properly for viruses. Much better to save the file to your hard drive, scan it manually with your anti-virus, then play it if it comes up clean.