Hi
Welcome to the forums!
First, it would be VERY helpful if we had the Full file name and extension so we can research it and see if it's something that can be replaced, fixed, or possibly even malware that's causing this problem.
From what I can find with this little info of "nsl file", I get that it can either be a "Nokia Startup Logo" file, or possibly a "Neural Simulation Language", or even "Net Stat Live", a Network monitoring tool from AnalogX but without knowing if the nsl is the file extension or the actual file name, it's near impossible to properly research this any more.
Please post back with Exact information on this file if you can, full name and extension. Plus where did you get this modified Vista from? I've never heard of Nvidia releasing a modified Vista version and I doubt MS would allow that in the first place, so it makes me think someone has released a cracked Vista version they called this "Revolution" or something, but it's almost certainly not a Vista version released by Nvidia.
Can you tell us exactly what you have here?