Hi, there, why I even can see ads of third parties when I'm broswering pages on steam PC client?

[icdcom]

Such as the one I just saw
--------------------------Fastest VPN...............

Well, I'm not able to post the screen capture here.

Thx, anyway, :D.

[Tev]

Sounds like your computer is infected.

Give this a run: http://downloads.malwarebytes.org/file/mbam/

[76561193857876471]

//edit// Teutep is just too fast.

You have malware/adware on your computer. Download Malware Bytes, update it, then do a full scan of your computer.

[J4MESOX4D]

Change your Steam and associated email password to be on the safe side too once your PC is clean of any lingering Malware material.

[icdcom]

Originally posted by Teutep:

Sounds like your computer is infected.

Give this a run: http://downloads.malwarebytes.org/file/mbam/

I trusted windows defender, and dat's the only protection for my pc,

[76561193857876471]

The best security is safe browsing habits.

[Tev]

Originally posted by icdcom:

Originally posted by Teutep:

Sounds like your computer is infected.

Give this a run: http://downloads.malwarebytes.org/file/mbam/

I trusted windows defender, and dat's the only protection for my pc,

Run a scan using Malwarebytes.

I wouldn't trust Windows Defender one bit regarding this.
I'd also recommend an actual antivirus too.

But, like moeroris said, even more important is safe browsing habits.