Try using Tesla to see if sys-patch and sigpatches are working properly. Also, the errors might be related to something else. Bad installation files, maybe? Were these defective games working before you updated?
Edit: to install Tesla...
Extract the latest
nx-ovlloader zip to the root of your SD card
Extract the latest
ovlmenu zip to the root of your SD card
Reboot your console and try the combo of "hold down L and D-Pad Down and push on the right joy stick" (all 3 at the same time). The Tesla menu should appear on the left side of your screen.