from what you have said it looks like you have switched the video mode in avalunch to PAL , you should be able to get it back to your video mode by going into the bios setup on boot and choose System / standard eeprom scroll down to TV Mode and change to your TV mode setting.
If you cant see the screen to get into setup, then you can do this, have the xbox off and hold down the black button on the usb adaptor while you boot the xbox (keep holding it down for about 10-20 secs) this will restore your eeprom settings (which include original video mode) when you 1st installed evox V1.3 bios.
Regards PaulY^