Bootlog.etl

I have a file called "Bootlog.etl".  It is in directory C:\Documents and Settings\All Users\Application Data\NortonInstaller\Logs\8-30-2008-09h53m49s.  Whenever I boot, the file starts at zero.  But it grows very quickly.  It is now grown to about a gig in size in less than 12 hours.  It continues to grow until I re-boot the machine when it resets to zero.

 

Is this really a necessary behavior to have a file that grows in this manner?  It not only uses a lot of disk space but it fragments my hard drive significantly.