I have Internet Security 2011 and have noticed a lot of these entries in the history log. Unauthorized Access Blocked (Access Process Data) the Actor is always C:\windows\system32\$sys$filesystem\$sys$drmserver.exe and the Target is one of two Norton files either pifsvc.exe or nswuitray.exe. I get several entries a minute, 30 to 35, for this.
I ran a full system scan and it found nothing. I have had NIS2011 installed for about a week and this just started last night, when I first noticed it, I believe the full history log file stops listing this on page 29.
I did download a .pdf file last night and when I opened it it locked up adobe reader around the same time I noticed this by checking the history in NIS2011.
I have not noticed any problems with the computer I just happened to check the history at that time and thought it was odd since I did not have any entries before that.