Mits you are a champion, I reinstalled mumble recently and the overlay was enabled by default. Disabling it fixed my issue. Thanks so much dude

Running Steam as admin doesn't seem to work either. Wow this is frustrating.

I've verified the Cache and everything is 100%.

Hey thanks for the reply, I've tried removing the launch options with no success. This happens for other games as well, but at the moment I have none installed since I reinstalled Steam recently.

Hi.

I've been having an issue on and off for a while recently, involving launching TF2. I click 'Play' and the normal grey launching box comes up. Soon after the box disappears. Then there's no game launch, however I appear to be 'In Game Team Fortress 2' on my friends list. This lasts for about 5 seconds, then I return to being just 'Online'.

I fixed this for about a day by reinstalling Steam and TF2, but now the issue has returned.
My laptop is perfectly capable of running the game, and I have played 2.5k hours without this issue.

My launch options are as follows: -dxlevel 80 -w 1366 -h 768 -console -novid

Any help would be much appreciated. Thanks.