The Solution, Finally!!!
Make sure the AUX volume is not muted. Confession: Mine has been muted for 18 months while I tried various drivers and tricks to make Giga Pocket work. The trick is that Giga Pocket uses AUX volume which is not used by many (if any) other programs. Therefor it will seem like your volume is on and all sound is working except for Giga Pocket. I was amazed to find my AUX volume muted and to find such a simple solution.
Follow these steps to enable the auxiliary audio port in the Microsoft® Windows® XP operating system.
(from Sony's knowledge base):
1. Click the Start button, and then click Control Panel.
2. In the Control Panel window, under Pick a category, double-click the Sound, Speech and Audio Devices icon.
3. In the Sound, Speech and Audio Devices window, in the See Also box, click Advanced Volume Controls.
4. In the Volume Controls window, on the menu bar, click Options.
5. On the Options menu, click Properties.
6. In the Properties window, in the Show the following volume controls box, click to select the AUX box.
7. Click the OK button.
8. In the Volume Controls window, under AUX, click to clear the Mute box.
9. Adjust the volume slider to the desired level.
10. On the menu bar, click Options.
11. On the Options menu, click Exit.
Note that not all systems have an "AUX" volume setting, but maybe this will help a few naive users like myself who have been struggling to fix this pesky problem while unknowingly having their sound muted.