When I try and access the CSS, the game freezes with that loud beep. I don't think my sc_selcharacter is over the size limit (my current size is 3.57, if it helps). I think it's also worth mentioning I have custom CSPs for everyone exept G&W and I'm using Riivolution.
At what point is it freezing?
When I pressed group it froze.
Your sc_selchar may be corrupt. I'd open it, extract all of your textures. You can probably to the whole char_bust_tex_lz77. Then download a fresh sc_selchar and put in your char_bust_tex. Try that and if it doesn't work, you may need to replace each csp individually, but I really doubt it. Have you changed anything else in the sc_selchar or common5?