I just downgraded back to Rebug 4.21.2 and its now working fine. I couldn't load anything in Rebug 4.30.1 as it turned off and flashed red.
Now I'm trying a PSN PS2 game and it doesn't work. It turns off the screen and does nothing but if I press power it reboots without any beeps or flashes, just goes back to XMB.
This is exactly what it did in Rebug 4.21.1 so I'm not sure but PSN PS2 games aren't working for me.