Update 2: I tested it further and it seems that I even can't run only 1 account in Sandboxie. This could mean, that it's a Sandboxie problem, because using 1 account on 1 PC shouldn't be an issue for VAC. That also means, that changing MAC adresses in Sandboxie shouldn't help, because Sandboxie is the problem. I will try now to run 1 account normal and 1 account in VM and look that I have on both the same MAC adress.

EDIT: It takes longer till I get kicked if I run only one account. I was able tu running it over 30 minutes, some days ago I was able to run at least 1 account without problems in Sandboxie. Is the reason maybe that they are still make any changes on VAC?

About older versions: Like I said, I heard versions 3.76 would work well, but idk if it's true. I for my part wasn't able to run it on Windows 8 or Windows 7, it works only on Windows XP for me in a Virtual Machine. So maybe someone who have Windows XP Dual Boot can try it out.

Update: I tested it today and I'm not able to run up to 3 Accounts anymore. I don't know why it was possible at the beginning, maybe because I had Windows 8.1 instead of Windows 8.1 Pro, idk. I'm testing now if I'm still able to run at least 1 account (sandboxed).

About killing Sandbox Service: Me and another guy already tried it, still vac kicks.

@Kottonmouth Soldier good idea, worth to try it. So VM's working because of different MAC-Adresses maybe? About the 2-3 accounts per PC issue: I tested it and it works for me well, I was able to run accounts over hours and that is what I read and heard in other forums, that other people are able to do this too. It's strange that it's dont work on every PC, like it's an operation system issue or something? I will test it today again and test if only the new added accounts get vac kicked later or all.

Btw: One guy told me (he is running Windows 8.1 Pro, that's why I upgraded) that sandboxie still works for him without any additional settings (so everything on default like in your tutorial and newest versions of Windows, Sandboxie etc.). I tried top copy everything what he has, but it didn't helped me. Then he tried to add new sandboxes and accounts in this sandboxes get vac kicked while the "old" sandboxes were still able to run without kick. Then I heard from two different guys, that they still can run Sandboxie on Windows 7, maybe they have the same issue like the Win 8.1 Pro guy (means old sandboxes only). And also I heard that one guy was able to run Sandboxie in the 3.76 version without vac kicks (but I can't run this version on Windows 8 or Windows 7, just on XP in VM, so I didn't tested it till now in Dual Boot). I can't confirm this all, but at least about the Windows 8.1 Pro guy I'm sure that it's true. Also some people say "you just need to add the settings" or "there is an easy bypass possible".

I'm googling and talking with people since it stoped working for me on 14th February and all the information that I collected just don't make sense altogether, it's curious.

That's what I was thinking about too, but I don't know how. You can change or hide the MAC of your PC, but all sandboxes have the same MAC I guess. Would it work to install sandboxie more than one time and just run different Sandboxies?

Btw... I read in some forums, that it's possible to bypass the problem with Sandboxie, but this guys don't tell anything, even not for money. So it's maybe just bullshit or some people already found a solution. I tried different things with Sandboxie but couldn't find the solution to bypassing the VAC-Kicks. Maybe one of the more experienced guys who use Sandboxie so long have any idea? This guys in the forum said it's very easy, but like I said, who knows if they say the truth.

Oh, really? I thought it's for everyone the same, because I already often read that people can run up to 3 Accounts. I'm using Windows 8.1 Professional (64 Bit).

The issue is: If VAC is blocking Sandboxie for what reason ever, why is it possible to run 1 sandboxed account and even 2 in the same time without get kicked? The VAC-Kick happen if you run more than 2 sandboxed accounts and this is strange.

Filtering for Mac-Adresses would make sense, but again: you can run 2 sandboxed accounts and 1 normal without get kicked. So why is it allowed to play on 3 accounts from one MAC-Adress? What about VM's, where idling still working, does every VM have an own MAC-Adress?

Btw: Aren't there any alternatives to Sandboxie as program which would work for CS:GO?

Does someone has an idea WHY it happens? I mean what is the problem for VAC with that? Are they filtering for MAC-Adresses or something like this? I don't know much about this all.

But I had yesterday an idea: 10 VM's are taking much ressources, you can run up to 3 accounts (2 sandboxed) at this moment, so you could use just 3-4 PC's for it. Why not just run 3-4 VM's with Sandboxie instead of this?