Error: Could not complete the operation due to error 80000012

Reason: 

While integrating the Silverlight XAP files into MOSS 2007 webpart, you will get this error. Because, your given path may not be in correct format.

Answer:

You may have mentioned the XAP file path like "\ClientBin\HelloWorld.xap".

Instead, use like "/ClientBin/HelloWorld.xap"