Everytime I have had a negative paypal balance from chargebacks or something like that, they never took money out of my bank account. I suggest closing your bank account though.
I read since Paypal lost a lawsuit some time ago they arer no longer allowed to dip in the bank account. Although this doesn't seem to have stopped them in the past. They sent a collection agency after me, twice, but that was it.
Now I use Stealth accounts only, if this ever happens I close the Bank account just in case and say bye bye to the account. Paypal can suck up the $$$ loss.