|Since two out of three computers never have this problem, the most likely issue is the computer itself or it's wireless interface.|
Most likely is the wireless NIC.
First, see if there are more up-to-date drivers for the NIC. If there are, install them. If that fixes the issue, you're done. If it doesn't fix the issue then it's likely a hardware issue and you will probably want to replace the NIC.
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.