Missing Perks/Skins/Achievements, unable to connect to server

[Eradan]

I got a new rig nearly two months ago. Since then, everytime (with a few exceptions) I launch Killing Floor, I cannot access my perks, skins and achievements, and when I try to connect to a server I get this message:

An unknown Steam error is preventing you from connecting to this server.

If the problem persists please contact Valve for support.

So I contacted Valve support (I translated the following myself, the whole convo is in French).

1/ "Delete all files under \\steam except Steam.exe and the steamapps folder, then reboot"

I was able to play after the reboot, and after a few hours without shuting down the computer the problem came back.

2/ "Close Steam, delete the steamapps folder, start Steam and reinstall the game"

No change.

3/ "Uninstall Steam, and install a new version from http://www.steampowered.com at the root of your hard drive"

Still no change.

4/ "Try the answers in this thread: http://forums.tripwireinteractive.co...ad.php?t=51908"

Totally irrelevant, and (of course) nothing works for me.

5/ "Please give me a screenshot of the problem"



6/ "Could you give me the msinfo report?"

Here it is! File

7/ "Make sure your network is properly set up for Steam. Also, disable the softwares listed in this message"

Doens't work, even when I totally remove the softwares listed.

8/"Try this."

Did it a dozen of times in 6 days, didn't work.

9/ "Have you tried to ask for help on the Tripwire forums?"

Well it's a Steam error, but here I am.

So I need help. Killing Floor is currently the only FPS I play, and I'm not playing it for nearly two months

I must add that sometimes, the game allows me to play for a few hours. Then I quit KF, do something else, and it's gone again.

[Eradan]

So nobody can help me?