Do the following:
1. Select the speaker icon that represents the inserted music on the slide.
2. Select "Slide Show" | "Custom Animation..." menu item.
3. On the "Custom Animation" pane, select "Add Effect" | "Sound Actions" |
"Pause" menu item.
4. Add a new shape (say, an oval shape) on the slide.
5. In the "Custom Animation" pane, select the drop down box of the pause
effect that we added in step 3.
6. Select "Timing..." menu item. You should get the "Pause Sound" dialog
box.
7. Click "Triggers" button.
8. In the "Start effect on click of" box, select the oval shape that we
inserted on the slide in step 4.
9. Click OK.
Now when you click on the oval shape, it will pause the music. Click the
oval shape again and it will resume the music.
- Chirag
OfficeOne Animations - Add over 50 animation effects to PowerPoint
http://officeone.mvps.org/anims/anims.html