this worked fine while having this problem back
understand you have this on Rebug 4.21.1 unintentionally clicked the OtherOS option without having OtherOS setup ?
try the video reset - force GAMEOS boot
** force the GameOS to boot ** To force the PS3 to boot into the GameOS
shutdown the PS3, then press and hold the power button on the front of the system until a beep is heard, then release the power button.
The video mode and boot flag settings will be re-set to the defaults and the GameOS will boot.