|If it were an IP address confiict the one party would be seeing nothing while the other person was connected and using that IP as they (the first party) wouldn't be connected to the network. If both parties are set to DHCP then there shouldn't be a conflict at all.|
Not only that but typically windows will tell you if there's an IP conflict with another device.
I suspect whomever connected either was doing something very bandwidth intensive (downloading big files or streaming video, etc) and was hogging all the bandwidth, or, they got into the management interface and blocked the first party.
Regardless, StuartS is 100% correct. The owner of the wireless network needs to secure the wireless network using WPA-2 encryption and a complex key.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.