Hi Everyone!
I've discovered your solution as well. I had recently not been able to load Windows Movie Maker, and in going to the Dell support website, found this question. After viewing the symptoms (hehe) that jwbonnett found wrong, I realized I had the same issue as well. No Audio Device, non-working speakers, no yellow exclamation points, etc. etc. Basically all the problems that he had, and including all the problems other commenters have had.
It was through the last commenter, although there are easier steps, that I solved my problem. I'll try to make these as clear and easy as possible (because it is just that, very very easy) What I did is go through the Dell Website search >Dell Support >Dell Drivers and Downloads >Chose my Desktop model, which happened to be the Dell Dimension 2400. I'm sure it does not matter for any kind.
Looking at mine, I first followed the commenters steps of going to chipset. For mine, there was (1). For others, there might be more then one. This was the Intel-Driver Version 4.04.1007 update. It went all the way back to 2003. I recommend for other computers that if there is a more recent update of the simaliar name, use that update instead.
Save it in an easy accessable folder. Of course when you pull it up again, it'll save in its own designated folder. Picky Computer, I know. Anyway, its a very small file... of about.......... oh at tops 20 something MGBs. Typically very small. So I downloaded that, took approximately... 3 minutes. RESTART YOUR COMPUTER RIGHT AFTER. IT COMES INTO EFFECT IMMEDIATELY THAT WAY.
After that I re-entered the Dell website, same entering steps, but this time clicked Bios. There's (1) However it asked for a hardware disk. I didn't have one. So it pretty much said "Screw you" and wouldn't download it. I got by just fine without it, but if you have a hardware disk and want to download it, feel free, it's a waste of time to me. Didn't help me at all anyway.
Went back to Dell, went to audio, and hoped for the best. There was a 2003 update for Sound Blaster, a 2005 update for ADI 198x Integrated Audio, and a 2005 update for Sound Blaster. Thinking I was wise, I chose the 2003 update for Sound Blaster. But how can you update Sound Blaster when you don't have Sound Blaster? You can't. Therefore, it yelled at me, and wouldn't let me download it. Figures.
So going BACK to Dell, I decided then to pick the cool ADI 198x Integrated Audio one, and clicked download. And what do you know! It actually worked! There was a big picture that filled my entire background too! Happy people and everything smiling at computers. If only they knew.... Again, easy accessible file save, then being the picky one it'll save on its own place. RESTART AFTER AGAIN. Don't be a restartless fool.
And after my WONDERFUL Dell Dimension 2400 came back on, vwala! Windows Movie Maker happily presented itself to me, the sound YELLED it was working when I clicked on a video project, and checking control panel, everything was clickable and on again.
Thus the story of about an hour. But you can do it all in about 15-20 minutes. So remember, just download the Chipset (you possibly may not have to, but I wouldn't risk it) and the ADI 198x Integrated Audio. And everything will be back to normal. For other computer users, follow similiar steps and you should be good. YOU DO NOT NEED A BIOS DOWNLOAD.
I hope my rambling helps everyone! :)