It definately supports underscores.
Darling_Jimmy: Everything appears to be in order. Hmm... this message appears on the sign up page:
Array ( [0] => 00000 )
Is that normal?
That a line that I put in for debugging. It really shouldn't be there anymore (I've just gone and removed it from the code). What Array( [0] => 00000 ) means is that there is no database error and everything is working fine. I have no idea why it has been giving you trouble.
Darling_Jimmy: EDIT: Dag yo.
Does that mean it worked? I'm sorry you've been having such trouble.