unauthorized access blocked

I recently installed the NAV 2009 update, a freebie till my subscription is renewed.  Ever since then when I check my "history" it shows "unauthorized access blocked"  .  Actor:  program files\windowsdefender\msmpeng.exe 

  Target: programfiles\NAV\engine\165.0.134\MCU132.exe   Action:  Open Process Token

 

What is causing this and should I be concerned?  I have Windows XP Pro.  Thanks for any info.