to be honest I wouldnt know, but im taking a shot here.... I would gess that its logging not just the parent but also the child/file that you open. That said you need to find out what kind of audit logging you have enabled on your site. Also audit log OOB is kinda broken and doesnt work properly as you have found out. I had a quick lookup and found a great article on msdn on logging:
its very big as you can customise it but I would think this is what your looking for:
Item-Level Auditing with SharePoint Server 2007
Having said that and shown you that I wouldnt still know if its possible as that feature was pulled by ms for some reason, I dunno i think it could of been taxing on the server?
alas all is not failed you also have this great article on the subject:
have you looked at audit policy?
Check in /Check out
the options are;
Opening or downloading documents, viewing items in lists, or viewing item properties
Checking out or checking in items
Moving or copying items to another location in the site
Deleting or restoring items
you can check anyone of these for the list by going to the list, then click on settings, then select list settings, under permissions and managment select information managment policy settings, check the radio button define a policy and click ok, fill in info as required but the part you want is Auditing so check Enable Auditing if it isnt already, You should get the selection above to choose from. If you want it to do more or less than that then you will need to make your own as iv shown above.
hope this directs you into the right direction :)