Seriously, take the strings off it for a while...
It sounds like the tension in the strings is severely outweighing the tension in the truss rod and causing it to bow badly.
Basses do sometimes do this, you're best off with an aluminium neck :)
(
Sonic James Doom forgetting the date since... umm...,
Mon 18 Jun 2007, 10:52,
archived)
I have done!
Left them off for a week, made only the slightest difference.
I think it's just her, she's stubborn.
(
Captain Wow currently being a cunt in Infamous,
Mon 18 Jun 2007, 10:55,
archived)