You are not giving very much information to go on, but I am guessing that you are running Windows (7?) and that you have downloaded the drivers from http://opennethome.org/hardware/install-tellstick/.
The most likely cause is that you still have some drivers from Telldus center somewhere in there. Unfortunately they don't play nice with standard VCP-drivers. My suggestion would be to uninstall the Telldus SW (if you have any) and unistall the driver you see (by right-clicking in the device manager) and reboot the computer. Then try to install the drivers from OpenNethome again.
Hope this helps!