ERROR: Could not open file vstdlib_s.dll

[BDNeon]

So yeah. When I tried to boot Steam up today, it started downloading an update, then when it reaches 100%, it flashes this message for a while, then automatically closes.

ERROR: Could not open file vstdlib_s.dll

EDIT: I just checked the thread below mine with that similar problem, seems it's damn Avast with a false positive, was fixed by temporarily turning off the real time shield. Hopefully Avast gets on this and removes that false-positive.

THIS IS A FALSE POSITIVE FROM AVAST ANTIVIRUS. TO FIX THIS:

Originally Posted by Danbri

Go to Real-time Shields, File System Shield, Expert Settings, Exclusions, add the Steam folder.

[jayden59]

I jsut got this message casue I recently kept geting that only one instance of steam can be on at once message so the other day I just reinstalled steam deleted all folders except for steamapps and steam exe and had it re up date it still to fix it , so when this message came up after trying to play batman arkham city and it shows like it starts to run and then nothing this poped up I thought hmm maybe Ill reset it. and then That error came up lol just my luck but I turned off avast and it updated.. Thanks for the help man

[WolfzheaD]

just been getting this too. rather than disabling the file system shield in avast though i've simply added the steam folder as an exception. probably a safer option mate.

[BaSeBallDuDeR]

Holy cow me and you got the same error at the same time. You fix worked I just had to disable Avast for like 10 mins and then it worked. That was a weird error

[the shark]

Just got this today, too. Google for the win.

Disabling Avast worked, and adding the Steam folder to Exceptions worked, too.

<3 the Internet.

[xidaranthed]

So, I had this issue, and turned Avast off for 10 minutes, and while Avast is off, I can boot Steam, once Avast comes back online, none of my games work. I get everything from "Failed to Authenticate" to "Client already running" to "Load through Steam client". What's going on?

[GibletsofJesus]

I'm using avast and I got this as well. This happened after I had to restart steam because I couldn't play any games because each game said that the Steam client wasn't open.

Anyway, according to avast, 4 of the vstdlib_s.dll's are identified as "Win32:Malware-gen" so either we've all contracted a lovely virus which infects our steam folders, or (more probably and hopefully) Valve just made a little update to Steam which Avast didn't entirely agree with.

[Mr SmokesAlot]

^ Actually it's the heuristics in Avast that's messing up. So until a specific definition is made by Avast, you'll have to live with it (or exclude the steam folder which you should have done anyway).

[xidaranthed]

Which Real Time Shield do I need to set Steam to be excluded from? I'm having trouble with this.

[Paul_cz]

Just had the same problem...I guess either avast released bad update, or valve released file that was flagged as a virus for some reason, or it was that heuristics.
I put all my games folders incl. steam from being into exceptions, should have done that long time ago anyway.

[Danbri]

Go to Real-time Shields, File System Shield, Expert Settings, Exclusions, add the Steam folder.

Problem Solved.

[Urser]

Originally Posted by Danbri

Go to Real-time Shields, File System Shield, Expert Settings, Exclusions, add the Steam folder.

Problem Solved.

Thanks, this worked.
+rep

I've submitted a report to Avast marking it as a false positive. Let's just hope it isn't a real problem.

[vlad.aka.47]

Originally Posted by Danbri

Go to Real-time Shields, File System Shield, Expert Settings, Exclusions, add the Steam folder.

Problem Solved.

Thanks dude, it really worked)

[coolbaluk1]

Excluding it doesn't work for me sadly.

[Danbri]

Originally Posted by coolbaluk1

Excluding it doesn't work for me sadly.

Does Steam pull files from any other location on your computer for a game or otherwise? That'd be the next thing I'd think of.