Definitely +1

Don't be offended but how many years experience have you had working with software and the net?

I'm finding many people here in Zealand that simply stick to the consoles because digital and PC gaming can be a real headache.

But on top cleaning out your Steam folder, as ne-zavarej suggested, you might want to clean out a lot of your other tem and cache folders as well. First by using the orthodox methods of dumping cookie cache's through your browsers option menu's and then hitting the main junk file folders manually (your worst enemy is the 'Temp' folder located in c:\Users\*name*\AppData\Local ).

I would follow up running a small handful of cleaner for both junk files and registry errors - CCleaner, Advanced System Care and Little Registry Cleaner do a good job without disrupting anything.

Afterwards I'd also run your operating system's built in disk defrag and do a follow up with Auslogics Free disk defrager.

It sounds like you've got a lot of tangled files and bad registry entries.

However, in the instance your an MS professional or something like that - then I'd assume 'virus.'

Should not be. I got mine in D:Steam/, and have never seen this either.

what about installing in several directories? I keep all mine in the same place.

^This! :-)

I got banned for 'Promoting Piracy' from the *new* forums. I got tired of creating topic after topic asking how to keep Steam from 'scoping' my system while running games because, whatever update they did after that NSA incident (told you all that Dot Net was watching you ;) ) was causing the Steam client to wait until I went full screen in one of their games and then force probed my system harder than ever draining all resources and making Skyrim cry.

So I popped back up in a new thread offering that it might just be easier to use a noCD fix to liberate Skyrim from the Steam client.

Well rather or not they were upset about the 'Steam Scoping / NSA' thing or I was the first "hardcore pirate" they had ever seen pass through their boards - I got permanently shit canned from the new main boards.

Yes I have had this happen multiple time too. Steam delete part of the game data then redownloads. I have seen the complaint alot recently and after years of this occuring valve still ignores it.

I am starting to think they are doing it intentionally.

You crack me up, Licurg!

http://www.youtube.com/watch?v=ToxCOZdYjDU

This one is from a couple of days ago... ;p

Which games does this happen in?

There are some, like Team Fortress, which are not deleting anything but they are forever updating. At one point I think I might've gone $75 over my bandwidth allowance in stupid hats.



Either way, anyone new to PC gaming needs to learn the Pyramid Scheme:

The Unholy Triad:

1. All Seer = EA
2. Lil' EA Jr. = Steam
3. BioWare = Hopes to grow up and become EA one day but is having a hard enough time losing it's virginity.

As programmer I have a lot of experience with software and I'm using PCs for like 20 years (well, first it was Amiga), so I guess it's not a problem with me being a newbie ;).
I never have problems with my system and I always keep it nice and tidy. On top of that I've bought new hard drive a month ago and I decided that it's good opportunity to re-install my OS and all software, including Steam. So my system, drivers, Steam and all games are pretty fresh, but it didn't help and this problem reoccurred a week ago when I tried to play L4D2.

No, they are all in the default folder. I'm using only default folder. No, I didn't. I will try if this problem will occur again.

Well, I checked Steam forums few minutes ago and there are plenty of topics about that. It seems that many people have this problem, but best 'solution' suggested on forums was "Keep backup copies of all your games on HD, so you will be able to re-install your game quickly when it will occur again". No, thank you ;). I'm using it only for Steamworks games. I like way too many great games that are Steam exclusive to stop using it.

.
.
Unfortunately Steam has a lot to offer despite how often it slaps their users around - So it is a Steamed if you do and Steamed if you don't situation.

And, yeah sounds like you know more than me so I'm guessing a virus

EDIT:

Reading through that thread back in 2012 it would have been nice if everyone would have listed their specs and make and manufacture of hardware. It might be result of a bad hard drive circulating at that time hence why it was just a portion of users affected.

But what I'm guessing is that something was corrupting or removing only a portion of the game and leaving back enough information causing Steam to believe the games were still intact.

At that point, if possible, running a integrity check might put that games back together but won't fix whatever is corrupting the data in the first place.

If this isn't happening to all of your Steam games then I would manually delete the games folders in Steam\Steamapps\Common causing the problem and using a cleaner like CCleaner to try and fish out all the left over tendrils and then start back again from there.

Here anpther one that is thinking the same, I've the retail edtition of X3 Terran COnficlt, that can be redeemed in Steam, I'm never have a single trouble with the retail version, but I'm need to reinstall the Steam version at least fourt times, usually by steam deleting games files.

I'm not sure whether I've ever had this precise problem since I don't keep a record of these things but I sympathise with the OP for his having to wait over 40 minutes to play a game when he's arranged a multiplayer session. I had a different problem last night but it had the same effect. I don't play Steam games very often so occasionally I test them to see if they're still working or if there's been a Steam update or whatever.

Yesterday I had launched Fallout New Vegas successfully - no problems there - but when I tried to launch Half Life 2 I discovered that, you guessed it, Steam needed to update. That wasn't the end of the issue, however, as even after the update had finished Steam then started to "download missing content" for HL2. I've no idea what this "missing content" is or does or why it suddenly needed installing after all the time HL2 has been on my HD but the whole process from updating the client to being able to play the game took about 45 minutes - so much for instant gaming then ! This is one of the many reasons why I don't like having to play games through the medium of a client.

A more common problem I've had is Steam RE-installing games which I've deleted, seemingly on a whim. The first indication I get is that my HD space is suddenly reduced by several GB ; it is only later that I discover what has happened : Steam has silently re-installed a game (e.g. Dota 2) which I had deleted. This is very annoying. Perhaps there is a way to stop this happening (?) but if so I don't know what it is.

And just like the OP I would first ask such questions on GOG 's forums rather than Steam's as I've heard bad things about the latter.

It has been a few over a few years.

Dark Messiah might and magic multiplayer
Shank
I think portal
One or more of the Half life 2 bits, that is HL2, Episode 1, or Ep2.
The Ball
I think Serious Sam classis TFE
I am pretty sure it happened with Red faction 1 or 2

I don't think it has happened with Team Fortress 2.

I know for sure it has never happened with Oblivion or Unreal tournament 3.

Aver and I seem to be in the same boat.

Also if you want to know my HDD is a Western Digital caviar black 1TB 7200RPM.

As already pointed out this is not the steam support forum.

But if this happens again, try to use the option "check local files". Most of the time the check will be quick and maybe only a few MB are missing/altered.