Hi,
I have not seen this behavior before, but can look into it. A couple of things that would be helpful to know are the DAQ card, that you are connecting the 2345 to. Also what is the error number you get, and any description it gives you. Let me know those things and I will see if I can find information on it or reproduce it failing that.
I would also recommend looking at changing from VI logger to LabVIEW SignalExpress. LV SignalExpress is released with the DAQmx 8.5 driver, which works find with the hardware setup you are describing, and gives you a much cleaner and easier to use interface to log your signals. There is also a utility for converting VI logger data to be used in LV SignalExpress if you are worried about converting logged data. You can get access this driver at ni.com. just go to the support page.
Let me know that information and if you need any help getting signal express setup. It is a really awesome solution for taking thermocouple readings, and is far easier to use than VI logger. It also has a lot more capabilities, that I think you will find very useful.
Have a great afternoon,
Michael D
Applications Engineering
National Instruments