Does the first one work and readable on the Workstation 5?
Is the second USB drive used on the Workstation 5?
The 256mb could be a format windows does not recognize. However, if the workstation 5 sees it, then it an issue.
Insert the 256 stick into your laptop. Press the Windows Key and type: Device Manager. Open it.
Expand USB Controllers (Universal Serial Bus). Make note of the items that are there.
Unplug the usb, You should see something be removed.
If you don't see anything disappear, then right click on USB Controllers and click 'Scan for hardware changes'.
If you still don't then there could be an issue with the card. You can also try a different USB slot.
Sometimes this helps and works as the computer will register the driver with this slot, which sometimes makes the computer force
itself to load the driver so you should see it then, even it theres an error.
You can also try another computer.