I recently installed the Large Original Blue Neon Theme and ever since I have had a few problems...
The number one problem is with the psp web browser:
A picture will describe it better then words.
I have tried restoring the default font, restoring the gb3s1518.bwfon and jpn0.pgf and restoring the text input screen and so far none of those ways work.
Also the custom fonts screw up the applications (Restoring the default psp font just make it (The font) have a huge shadow.)