Norton Power Eraser

I downloaded and ran NPE last week and now I have a file on my system that steadily gets bigger & bigger until I need to restart the PC. The file is NPETraceSessionBoot.etl and is in C:\Documents and Settings\[user]\Local Settings\Application Data\NPE

 

I cannot delete the directory as it says it's in use.

 

What is using it and how can I stop this and delete the directory?