What's Arduino board are you using? some model which using DTR or RTS signal for auto reset control may problem on Hyperterm..
because Hyperterm open COM port with handshake signal control , that your Arduino may still on reset state.
remove autoreset pin and set Hyperterm handshake as "None".
It'll work properly. ;)
I'm using the Deicimila.
I don't think it is staying in a reset state because if I have the Arduino only sending data, it works fine and the data shows up in hyperterminal. It's when I try to send data from Hyperterminal to the arduino that nothing happens.
When I open the serial terminal in the Arduino IDE it resets the Arduino as the terminal opens, which is something I wanted to avoid, but knowing it does this, it's not a huge problem.