原來,是 server 2003 預設是不支援 .xaml 檔案的 MIME 格式。所以,就要手動去 IIS 上設定了。
到 IIS->預設網站->內容->HTTP 標頭->MIME 類型->新增
在副檔名、MIME類型 欄位都填入 .xaml 即可。

參考網址:
1. silverlight question
2. panda & polly 的努力
Event 順序 | Event 說明 |
1. initializeRequest | Raised before processing of the asynchronous request starts. You can use this event to cancel a postback. |
2. beginRequest | Raised before processing of an asynchronous postback starts and the postback is sent to the server. You can use this event to set request headers or to begin an animation that indicates that the page is processing. |
3. pageLoading | Raised after the response from the server to an asynchronous postback is received but before any content on the page is updated. You can use this event to provide a custom transition effect for updated content. |
4. pageLoaded | Raised after all content on the page is refreshed, as a result of either a synchronous or an asynchronous postback. You can use this event to provide a custom transition effect for updated content. |
5. endRequest | Raised after an asynchronous postback is finished and control has been returned to the browser. You can use this event to provide a notification to users or to log errors. |