I g00gled my ass off but couldn´t find anything that helped it or described the problem as it occured for me. Finallyfound some entry on the steam forums tho.
The problem seems to be the last update from the 22nd of November.
SOLUTiON was posted HERE at the bottom of the page.
My operating system is Windows XP SP3 (yeah Iknow

Edit: For it obviously bein an updated related shor term issue I posted it here and will ask a Forum´s admin to put it into the "I want to burn my PC" section after the probable first wave of ppl searching for a solutiob for that as well.Originally Posted by bledd View Post
SOLUTION
Yup
That worked for my brother too.
Delete the folder...
\Steam\steamapps\USERNAME\team fortress 2\bin
Run TF2 and it will recreate the folder with the correct files in it.
Now pressing M or Esc works correctly
