Janaleemac..
Unless AVG is reporting a problem/infection with the locked files, it's normal and nothing to be concerned about. There are a number of system files, which are locked and reported by AVG as "unable to be scanned". If you have any doubts about some of the files, you always have the option to post a copy of the report, at our AVG Forum at CNET. (Or the Spyware, Viruses & Security forum ) Otherwise, you have the option to exclude the "locked file scan" report from showing.
I don't use AVG as my A/V, but according to this post at the AVG Forum, in order to not have the locked files scan report show:
'To see the setting for a manual scan, select "Change scan settings" under Scan whole computer on the Computer scanner page. Select "Set additional scan reports..." on the next dialog screen. You will see a bunch of options, one of which is to report locked files. Uncheck it'.
I might have worded the above a little differently (and clearly) had I been using AVG.
I'm sure you'll be able to figure it out. If not....
"give a shout".
Please don't ever hesitate to ask questions. You'll find the mods and members, more than willing and eager to help.
Carol