I think you may be related to your hacks.in file. Delete hacks.ini from your sd-card and extract 4.2u-hacks.zip to sd:\
Boot into priiloader, click hacks, enable block online updates and block disk updates, remove disk diag check.
Go to priiloader settings and set autoboot and return to system menu, check that ios is set to system ios (ios70).
Backup up the bootmii folder and nand.bin key.bin to a safe place, remove them from your sd-card.
Reboot, any errors?