Don't know if this is of any use..... cause don't really know what i'm talking about but....
I had a folder that was causing problems a couple of months ago.
I ran the virus checker and like you said it couldn't see it... I tried to manually delete it but it wouldn't let me. In the end i ran scandisk and and it found i and i was able to delete it from there.
Like i said don't know if that helps but worth a try maybe :)