My first impression is that your laptop card could be going. If you haven't made any recent system changes, this could be the most likely variable.
Just to double check, the IP for your card in the XP machine is 192.168.0.230, and the laptops is 192.168.0.200?
And when you have established a connection from the XP machine to the laptop, you are able to ping the laptop from the XP machine, but cannot ping from the laptop to the XP machine.
Could you give some more information on how you have your settings? I'm looking for default connection speed, host settings, etc.
The problem could be that the laptop got confused about how fast its supposed to send data, or where its supposed to send it to.