Yeah, I've got mine working..... sometimes. Just because it fails doesn't mean you've done something wrong, you just have to keep trying. I can't nail down exactly what it is/was that stopped mine uploading poi's. I formatted the thumb drive to fat32. I made sure to only use the express recommended setting on the Poi Loader. I deleted the custom poi's on the nav before putting in the usb. Sometimes when it gave an error on rebooting I just turned everything off... ie. ignition then open and close the door and wait till it all goes to sleep before starting again and then it would work. So go figure. Also make sure car is running when doing it, not just ignition on. And the path needs to be x:/Garmin/POI/Poi.exe, case sensitive as mentioned above. I then also wondered what if any size limit there was on the Poi.exe file. I've had it up to a bit over 800kb. I don't know if there is a limit or anything else that might stop it working or why it sometimes works and not other times. Bloody thing. lol.
Anyway, hope this helps.