Dell XPS 1640 Internal Speakers Not Working

I've got a Dell XPS 1640. My internal speakers don't work with itunes and most other applications. However, when I ran the Dell diagnostics, sound was produced. Dell tech support told me that its a software problem because there was sound in the diagnostic test. They checked the drivers etc which are current and recommended that I reformat back to factory settings which is a major hassle. I'm running Vista 64 bit, but do have a Windows 7 update disk which I haven't installed yet. They told me that installing the Windows 7 update wouldn't fix the problem. I've read about disabling IDT (which I've tried) wiggling the inputs etc. My external speakers work fine and I had Skype loaded which also produced sound which I unistalled to see if that was causing the problem (still no sound). Any ideas?
Thanks!

 

By any chance are you connecting to an external display using HDMI?

Also, try right-clicking on the volume control icon (next to the time/date display on the bottom right of the screen) and select playback devices. The speakers/headphones should be the default device (little green checkmark next to the icon), if not click on it and then click "Set default".

 

No external HDMI is plugged in. The playback device selected is the speakers/headphones. Thanks

Internal speakers don't work even though they do during the diagnostic test. External speakers work fine.

 

Hmm... are you using the Creative X-Fi software? I think that bit of software is completely garbage and always remove it.

 

I've got Soundblaster X-Fi MB.

 

Hmm, I might not be the best person to help you, as I'm not overly familiar with the differences between the 1640 and the 1645. Still, as far as I know for this laptop, the X-Fi stuff is just done in software, and as I found it to be very gimmicky and also problematic, I removed all of the X-Fi software from my laptop and just installed the latest IDT drivers and software.