I bit the bullet and installed the Metra 99-7803G in my 2004 Accord with navigation and everything works fine. Although I will say that the automatic climate control is not as smart as the OEM on. In other words, if it's 20 degrees and my auto climate is set to 73, in the OEM version, the air wouldn't start blowing until the car was warmed up, which would keep cold air from blowing into the car. The Metra unit just starts blowing and it has a hard time compensating between the cold and hot air to maintain the 73 degrees. But...I'm just confirming that we (Accords with navigation) do have another option and I do have a double din HU hooked up. A very nice addition compared to the radio that was stock.

I'm in the same boat as you with a 2004 Accord with Nav unit. Are you still pleased with the Metra 99-7803G? Looks like that's the only option other than trying to scrounge a used DVD player.

I have a 2004 Honda Accord as well and my navi has been resetting its self for the last 3 months. My battery went bad yesterday so I purchased a new one and now the screen just reads "Please check disc" now I can't adjust air or anything. Does this mean I need a new DVD set in the trunk?

If you send it off to these guys:

DVD Players Navigation MP3 CD Stereos Factory OEM Car Audio

...they will check the player and tell you. They have a minimum charge, but it does sound to me like your unit has gone south. If they can fix yours, they will do that. If not, you can get a refurb from them:

2003 04 05 Honda Accord GPS Navigation Disc DVD Rom Drive

Not cheap, but no issues with using all the controls if you go with the original unit. If you replace it with aftermarket, you will lose some functionality. I went with the refurb so as not to further confuse my wife.