What Promethean product are you trying to connect to through USB? Do you have the model number for this?
Please ensure you have the latest ActivDriver installed if you are connecting to an ActivBoard, this can be downloaded from article 10902 on http://www.PrometheanKB.com.
Should you be using the ActivPanel Touch, this does not require the ActivDriver as it uses the Windows touch driver.
Please also try connecting a direct USB cable bypassing any wall boxes or connection panels and connect directly into the Promethean ActivBoard or ActivPanel Touch.
Should you wish to contact us direct for this issue, please use reference number 00476513 and fill in the form on the below link: http://goo.gl/j3AT8S