Avira blocks TF2 Update/Game

[Entity Displeased]

I recently wanted to update TF2, but in the middle of the download it stops and Avira tells me that the File "TR/Patched.Gen" is a Trojan Horse. I tried adding an exception and reinstalling the game, but in every way it tells me that this file has blocked rights.
I´ve played TF2 at a friends´ house yesterday and it worked perfectly fine. Is it a Virus or just false alarm?

[Cathulhu]

Create an exception rule for the Steam folder and its sub-folders in your anti-virus program.
If the access is blocked, try restarting your computer.
It's a false positive.