I upgraded the firmware on my PNA to version 6, then discovered that some non-agilent sofware didn't support it yet. I "downgraded" back to version 4 successfully, but now the front panel keys don't work. The usb mouse and keyboard work fine, and I can access the functions of the front panel through a pull-down menu, but this is not very convenient. Has anyone else run into this problem or have an idea of how to fix it? The PNA help suggested re-booting with no usb devices and then re-connecting them (this didn't help).