Just wanted to say a BIG THANKS to Royorlev. I trawled the web for fixes for this issue and this was the solution.
Another solution was to delete all the installed usb devices from the registry and allow them to be reinstalled. That didn't work.
Another was to try mem stick on another pc. Mem stick was fine on other PC so that got me nowhere.
Another was to reformat the drive on another PC. I did this and still it failed to appear on my home pc.
Another was to switch drive letters around. Use something never used before. I tried 3 diff letters at both ends of alphabet. That didn't work.
I downloaded that SPTD install file, went to safe mode and ran it with remove, rebooted and plugged in the mem stick and hey prestoroony, G: was open on my desktop in half a second.
Many many thanks.
p.s. the above links to the install files failed for me, i had to go to
http://www.duplexsecure.com/downloads to find the installs.
Happy 1gig USB stick user