Which operating system are you using? Which version of the PicoLog software is installed?
The driver may have reported an issue - please undertake the steps listed under the 'Resolution' section of the following page on the Microsoft website:http://technet.microsoft.com/en-us/library/cc725873%28v=ws.10%29.aspx
This will uninstall the driver for the TC-08 and then reinstall the driver.
If the driver is correctly installed you should an entry for a 'Pico USB TC-08' in the Windows Device Manager:
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