Have you tried using a regular USB cable?
If your version is 2.x or higher you do not need a midi to usb.
At the bottom of this doc are instructions on how to determine your version.
Also make sure you have the newest Monkey and drivers for your OS.
You can also use Gearbox instead of Edit with the PODxt.
don't forget that you can also use gearbox...
line6 edit is java based and tends to have more issues....
you might try removing all versions of java and then installing the latest if you have to have edit....
but as i said, gearbox might work for you as well.
Plug the XT into your PC from the USB port of POD (the printer jack end) and plug the other into USB port of desktop. Make sure Monkey is installed. Line 6 edit should work fine afterwards. Make sure the XT is switched on before openning LIne 6 edit. Then with Line 6 edit you can find and edit all your new tones and then use the save button on the xt itself into whichever bank you have chosen.