Hi
Your issue seems to be generating alot of interest. I see people have suggested that you use various other OS and even no PC at all! I suggest that you try running your test again but this time try switching off your automatic updates and also your firewall, occasionally the security you have set on your PC can sometimes cause errors to occur when attempting to run things for a long period of time. Also are you running your LabVIEW program from the actual VI or have you built it into an installer? I suggest that you build it into an installer and run it as a deployment program instead of running it in a development environment.
I see that suggestions of using LabVIEW Real Time and Real Time OS has popped up and this would be the real way forward to absoloutly gaurentee that your test will keep running for as long as you desire. LeeM has pointed you towards the information on the NI website relating to this. Also the idea of not using a PC has also come up, NI have a piece of equipment known as Compact Fieldpoint which could prove to be useful to you.
Hope the information proves to be useful but I really do suggest trying to run the test again and see what happens
Kindest Regards
YatinM
NIUK & Ireland
Applications Engineer