When that error presents, does any error message present with it? If so, what does the message state? Does this present with any other computers at the school?
If you have not already done so, please download and install our updated 5.12 ActivDriver from Promethean Support here and re-boot the computer.
Also, If the USB connection in place between the computer and the surface uses any additional hardware (e.g. an extension cable or booster, a wallbox, an external USB hub or docking station), please instead try making a direct connection between the computer and that surface using only a single 3m length of A-to-B USB cable. Does this affect the appearance of or frequency of the error?