If you don't have resources in your project, than it should be empty as shown in your screen shot.
There are multiple files in my project. C::B even opens the main.c file as it normally would when I open projects. And it's like this for every project now, not just this one.
Do you configure to disable the tabs? Here is what in my C::B, see screen shot below:
Mine doesn't have that option (see picture). But I did notice when changing the settings here the tabs appear for a moment before disappearing again. I tried every setting here but none fixed this.

I will also say that I tried deleting the registry values to fix this after I uninstalled C::B. It wasn't like this when I first installed, so I don't know how that didn't reset everything do default, unless I missed some setting somewhere. If anyone knows how to reset C::B to default completely, please tell me. I think that may fix it.