Need Help To Replace Unleashx With Ms Dashboard Options

[Deniii]

I recently bought an used Xbox and it had unleashX installed.
The thing is I can't access the MS Dasboard. It gives the error 21. I tried manually loading a file named original.xbe but I still get the same error.

The thing is, I don't like unleashX and what I want is to get rid of it and replace it with MS Dasboard but I don't want to lose the function to play burnt DVDs. Can someone explain me how to do this?
I know it's possible because about 8 years ago, a friend of mine bought a softmoded Xbox that could run burnt DVDs and the dashboard was the original.
I searched a lot of forums but nobody wants to explain me how to do this. They keep insisting me on keeping unleashX because is better than MS Dasboard.
I don't care what other people consider better, I want MS Dasboard.

Please, if someone can give me a simple guide on how to fix the error 21 and replace unleashX with MS Dasboard, I'd really appreciate it.

Thanks.

[Heimdall]

HeXEn installs UnleashX as its primary dash, with Evox in case you want to try it, and gives you an option to install XBMC. You can then switch between then using inbuilt scripted tools.

You will have access to the MS Dashboard.

NDURE allows you to boot to a stock BIOS and dash which allowed you to play online, but Xbox Live is no longer available. You can now only play online with Xlink Kai.

The TSOP is the chip on the Xbox motherboard (1.0-1.5 only) that holds the stock BIOS. You can reflash it with a hacked BIOS instead of softmodding the Xbox.