from Torch:

Some new UMDs are detecting files in the ms0:/seplugins and ms0:/iso folders and causing problems, even deleting files from these folders.

This plugin will hide these folders in GAME mode so they can't be accessed.

To install, copy cfwblock.prx to ms0:/seplugins and make an entry in game.txt
e.g. ms0:/seplugins/cfwblock.txt 1