Overlay issues with Steam

Hello, for a few months now I haven't had an overlay on my games (Counter-strike: Source, TF2, Killing Floor, Saint Row, and others). I've tried everything:

- Updating Mumble
- Removing folders that start with "hl"
- Adding my game's .exe folder to the whitelist
- And more

So I'm calling for help and hope to get a response soon =s