This should fix your problem...here we go, step-by-step:
1. Extract all the files from the evoX.iso to somewhere on your pc hard drive
2. Copy the unmodified menu.ini file that should have come in your evolutionxv1_8_458_iso.rar file to the same directory that you extracted your .iso file to
3. Rebuild the .iso file (i use xboxisotool v1.1 to extract and rebuild my iso files, i can send it to you if you need it)
(or you can burn as data disc with prassi primo)
4. Burn this new .iso file to whatever media works in your xbox
5. Boot the xbox and load the cd you've just burned. If for some reason the xbox starts rebooting, turn it off with the disc still inside then turn the xbox back on. It should boot the EvoX from the cd
6. FTP to your xbox and replace the menu.ini file on its hard drive with one not containing errors (ie, change your menu.ini to read dash-ms.xbe instead of msdash.xbe). You can actually name your original dashboard anything you want, as long as you address it by the same name in the menu.ini file
7. After replacing the menu.ini file, take out your evox disc and reboot the machine. It should boot to EvoX from your hard drive fine