In Windows Mail, I cannot open EMI, WAV, WMV, JPG, JPEG or GIF attachments. In Windows Mail I have been to the TOOLS/OPTIONS/SECURITY tab and:
1. Checked the 'Internet zone (Less secure, but more functional)' box.
2. Unchecked the 'Do not allow attachment to be saved or opened...' box.
3. Unchecked the 'Block images and other external content in HTML e-mail' box.
Solved the problem. It took a complete reinstall of the Vista OS. Apparently the upgrade on only 1 GB ram did not allow all files to copy over correctly. Performing a complete install using 2 GB ram did the trick.
I recently upgraded to AVG 8 - I had problems / faults upon installation. Upon upgrading, my Windows Mail attachments would not open. I've uninstalled this and that has solved the problem ! Give it a go !