I do not have an answer for you, but found your post because I have a similar experience.
I have the WD Black 1T external hard drive that I use for backup. I have an iMac using OS 10.5.8.
My issue is that the ProtectMac AntiVirus app found a “potential” problem and identified the file. So I deleted the problem files. No biggie, right? Well, now, each time my system runs its scheduled back-up, the ProtectMac software keeps finding the same problem files…the ones that were backed-up on my WD external hard drive. So I try to to delete these files and it won’t let me.
Now it’s become so annoying because each time ProtectMac runs, it keeps finding the same same same same same same same same problem files, and for the life of me, it feels like “Hal” from 2001 Space Odyssey is forbidding me to delete.
How counter intuitive is that? Every other time I’ve wanted to “click and drag” files to the trash can, it does it. Why can’t I simply trash these files???
Anyone out there know? Thanks in advance!