Description: On WordPress 2.1+ and PHP versions older than 5.0.2, publishing posts using Writer results in non-ASCII characters showing up as either squares or question marks.

Reason and Solution: Writer erroneously prepends the UTF-8 Byte Order Mark to XML-RPC requests that are UTF-8 encoded. This prevents WordPress from correctly detecting the UTF-8 encoding declaration, so ISO-8859-1 is assumed instead.

Run regedit.exe and find the following key: HKEY_CURRENT_USER\Software\Windows Live Writer\Weblogs\<your-blog-id>

Verify that the subkey ManifestOptions contains a characterSet=”UTF-8″ value. If so, under the subkey UserOptionOverrides, add a new String Value named characterSet and leave its value empty.