I bought a new USB drive (Verbatim Store 'n' Go 8GB) and copied my Thunderbird Portable folder onto it. But the program usually won't load first time, coming up with an error message. Now, if I keep trying it will eventually load, but not the next time. If I copy the folder to an old USB drive it works first time. If I copy the folder to my desktop - it works first time. If I copy it to the desktop of another computer - it works. So presumably this has to do with the USB drive, but can anyone suggest where I can look to find out how to fix it, please?