Strange entries in my Webalizer report

I'm looking at my December Webalizer stats for my multisite at http://www.spi.us and I'm seeing some strange entries in the "Top 10 By KBytes" section. There are 7 out of 10 entries that indicate 0 files and 0 visits yet they're creating hits and using bandwidth. The 3 that are generating visits are recognizable but I have no idea what’s up with the others. I looked back at stats for a year and this seems to have just started this month. Can you offer any insight into what’s happening here and what I should do about it (if anything)? I'm already using WordFence on all my domains and I have about 25 of them on this multisite.

Thanks,
Larry