1. Your bootmii/boot2 is having some issues displaying. It's clearly seeing the SD card but it either unable to load the ppcboot.elf into memory or your Wii cannot display the video mode. Try a different SD card, Sandisk 2GB work well. Check the bootmii.ini file for video settings and ensure that your TV can display it. You will want to have this boot2 working just in case something untoward happens.
2. Some versions of Priiloader have this issue.