While trying to repair files with Norton Utilities, I get a message:

" The operating system, or another process currently has exclusive access to this drive, or some of it's files. Norton disk Doctor cannot continue with a repair under these conditions."

In the task manager, there is nothing running in the Application tab, but there are numerous things in the Processes tab. I tried ending the processes until the errors came up stating that the process were critical and could not be stopped, but NU still won't run. I made sure that my AV was disabled. What other processes would stop this from running?