There is a product called Total Traffic Control from Lightspeed. It installs a security agent that allows IT managers to control all removable devices on a workstation. Even if everything is set to “Allow,” it apparently runs a check on the devices and then disconnects them after they show as connected. Logger Pro will report “no device connected” because Total Traffic Control limits access to USB devices.
As of our last testing of this issue (in 2006), the only solution is to remove Total Traffic Control because it seems to be incompatible with USB devices that require continuous connection such as the LabPro.