Holy crap I'm gonna freak if this comes up again...

Please in the future PAY ATTENTION when you add stuff to your psp...
nitePR uses a completely DIFFERENT prx for 3.71m33, if you payed attention you would have noticed two folders.
One named "3.71m33"
the other named "All other firmwares"

Since you are no longer on 3.71m33, obviously you need the prx found in the "All Other Firmwares" folder.

Why? Because you are on an OTHER firmware besides 3.71m33...

So redownload nitePR rev K Stable if you don't still have it, and go into the correct folder (all other firmwares) and swap the prx in your seplugins folder with the new one...

Simple enough, your done...