Well, this kind of confused me so i googled it, and nothing popped up. I would think if this was a real .dll it would be on google, but not a single thing popped up. Also, av.exe is a son of a bitch. It's a nasty virus and is hard to get rid of. It's a fake virus scanner that downloads itself from a virus scan popup. You need to delete the file, it was very well written and manages to elude Anti Viruses. Scan SB S&D, it should find it as melware, fix that. Then go to your registry and delete it. When i had this, it was under either Persistence, Igfx, or AdwareAlert. Search HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE for those. After you remove those, if you found them you need to make sure they're gone. Restart you computer in Safe Mode and check both of those, if they're there delete them again and they should remain deleted this time.