You can use SeiPSP tool (search it if you need to or google it, yes you can get it from
www.psp-hacks.com or
www.pspupdates.com) or you can get your brew from
www.pspbrew.com and they have an option to hide the corrupted icons when you download them. Hiding corrupted icons has something to do with the file name and how many characters long it is, but I don't know the specific details.
You can also move all the corrupted icons to the bottom of the list by connecting your psp to your computer and selecting all the folders with the %. The right click and cut (not copy) and paste them to a folder on your computer. Cut them from your computer and paste them back to the psp and all the corrupted files will be at the bottom.