The extension ".asd" happens when the Auto Recovery feature in Microsoft Office is turned on.
Here is what I've discovered:
Recovering unsaved changes with AutoRecover
The AutoRecover feature was turned on before I loss of a document, but can't save or open the recovery file:
1. Start Word.
2. Click Open Button image.
3. Locate the folder that contains your recovery files (usually the Documents and Settings\username\Application Data\Microsoft\Word folder).
4. In the Files of type box, click All Files.
Each recovery file is named "AutoRecovery save of file name" and has the file name extension .asd.
5. Open the recovery file.
6. Click Save Button image.
7. In the File name box, type or select the file name of the existing document.
8. When you see a message asking whether you want to replace the existing document, click Yes.
Any recovery files that have not been saved are deleted when you quit Word.
If the recovery file doesn't contain your changes:
The amount of new information that the recovery file contains depends on how frequently Word saves the recovery file. For example, if the recovery file is saved only every 15 minutes, up to 15 minutes of work can be lost if a power failure or similar problem occurs. To change the AutoRecover save interval, enter a number in the minutes box on the Save tab in the Options dialog box (Tools menu).
Hope this all helps, if not, there is even more in the link.