Hello,
do you have enabled User Account Settings?

related to http://feedback.arma3.com/view.php?id=19708

This may sound stupid, what do you mean user account settings?

Sorry, it is User Account Control.
Could you please try to disable it and see if the problems stop?
http://www.howtogeek.com/howto/windows-vista/disable-user-account-control-uac-the-easy-way-on-windows-vista/

I tried all the different UAC setting, but nothings worked! My friend has had no issues but hes running windows 8.

I normally use a non-admin account on my Win7 x64 box to play BI games. If I start Steam normally, the A3 Launcher always says that "Steam is in offline mode," followed by "Steam service unavailable. Please make sure Steam client is running." The launcher will exit if click "Ok". If I start Steam as admin, the Launcher works. Is this behavior normal and intended? I can upload the Launcher log from my non-admin Windows account if that will help. Using A3 1.28.127008 stable build.

Hi OMAC,

thank you for reporting this. This is not intended behavior and it should not happen under normal circumstances. Typically, this problem happens when Launcher and Steam client are running on different security level (admin vs not admin), because Windows then prevents one process from seeing the other one.

Could you please run following command in the command prompt (cmd.exe) when "Please make sure Steam client is running" message is displayed:

tasklist /V > OMAC_tasklist.txt & start OMAC_tasklist.txt

and then upload the text file here as well as log files.

Also I'd like to ask you how do you start Arma 3 Lancher (are you starting it through Steam client or by invoking Arma3Launcher.exe directly) and whether you're starting it as Administrator (intentionally)?

I start Launcher by right-clicking on Arma3 game in left column in Steam, and selecting "Open Launcher," or I click Play for Arma 3, and then click "Open Launcher" in little window that pops up. I am starting launcher as NON-ADMIN user. If I start Steam as ADMIN, then "Open Launcher" works fine. I'll upload my files.

Hi,thank you for your logs and task list. Based on that I have a working theory, but I can't test it right now. I'll let you know then I test it, it meanwhile you can test it by yourself.

It seems that you're running an application (running with admin privileges) or a service that is interfering in communication between Launcher and Steam Service Host. I've seen that you're running a Killer Network Manager and this app may cause the issue. You can try to uninstall that Killer Network Manager or to kill the KillerNetManager.exe process AND stop/disable BFNService.

Killer Network Manager monitors my Killer Xeno pro gaming network card. BFNservice (Big Foot Networks) controls the card. Both packages start automatically on boot. It would make sense that there is a conflict between those packages and the Steam A3 Launcher. One time those packages had a conflict with iTunes network function, but the packages were patched to fix that.

However, killing the Network Manager and BFNservice does not affect the Steam Launcher function, as the same "Steam is in offline mode" and "Check if Steam client is running" errors still persist.

Hi,

could you please run following application from the command line and upload created text file here?

  Handle.exe > OMAC_handles.txt & start OMAC_handles.txt

You can download Handle.exe from here: http://technet.microsoft.com/en-us/sysinternals/bb896655.aspx

Handle output uploaded today. Please delete the files I have uploaded after you have them - for security.

Hi,
sorry to bother you again, could you generate list of handles once again? This time running command line as administrator? O:) The crucial part of information is missing from the file otherwise.
Thank you very much.

P.S.: Uploaded files were delete as requested.

Admin run of handle uploaded.

Hello OMAC,

thank you very much. Based on that list, your problems are caused by process RzWizardService.exe - Razor Wizard Service. That service creates a misconfigured communication pipeline preventing communication between Arma 3 Launcher and Steam.

This issue is not present in Dev-Branch, because we fundamentally change the way Launcher communicates with Steam and 3rd party apps can no longer interfere with it in this manner.

Unfortunately we don't have any workaround at this moment (apart from stopping the service or switching to Dev-Branch).

That damn service comes with this new Razer mouse I bought. You are correct, if I kill that service, A3 Launcher works even if Steam is run as non-admin. I don't use the Launcher anyway, so I will wait for next stable branch update before trying it again.

Hi,

the updated Launcher released with Arma 3 update 1.32 features new communication interface to Steam that is less susceptible to interference by 3rd party applications.

If you have any problems with the new version of Launcher please create a new issue ticket.