Uno works on one machine and not another

Using Arduino IDE 1.x
1

Arduino Uno
Set up a program on a Uno with W7 laptop. Can access the serial port fine with Serial Monitor.
Take the cable to another W7 machine and cannot access the program with the Serial Monitor.
Checked all settings and they are same. Using 1.6.4
Thanks
Phil

2

Solved
Serial port issues on the second machine.
Thanks,