Please make sure .NET 1.1 SP1 is installed. If .NET 2.0 is also installed it is possible there is a conflict between LabView and another application. Try uninstalling .NET 2.0 and then reinstalling the tktla driver. Any VI that was saved after opening it with this condition will need to be replaced with the prior version. If the problem resolves then there is a .NET 2.0 conflict with LabView and possibly another application. Please contact National Instruments if you need further support. Note: You can force any .NET program such as LabView to use .NET 1.1. This requires creating a .config file named "application name".exe.config and placing it in the same folder as the application executable. For example, to force LabView to use .NET 1.1 you would create a file called LabVIEW.exe.config. Place the following lines into the config file: <configuration> <startup> <requiredRuntime version="v1.1.4322"/> </startup> </configuration