Knowing the manufacturer of the PC would help..
If you purchased it from PCWorld or Currys, there is a way of running the removal tool and also an updated removal tool.
If you have a Packard Bell, remove it through the Smart Restore tool.
Have a look in Add/Remove programs to see if you can see NIS there.. If you can, try to remove it from there then run the tool. The tool cleans the registry.