zclient.exe deletes itself and changes my administrator rights

So I have no idea what is going on, this is the very first time I've experienced this. I was playing D2R for about two weeks now and everything worked fine up until now, at first I couldn't launch the game, it simply crashed and the shortcut didn't work no more because the original file was gone. I thought my antivirus decided to act on it even though I got no notification about it. So I wanted to copy a new instance there, but that's the funny bit, I couldn't. My PC screamed at me that I have no administrator rights. I changed the file location onto a different disk, launched the game normally, so it didn't really bother me that much, I decided to sweep it under the rug for the time and work it out later. Played some, exited the game, zclient.exe crashed and it's gone again. So I wanted to pretend the issue doesn't exist once again and download a new copy of the file... I couldn't. No rights to save files into location.

Every time this file shows up and touches a folder it changes administrator settings of ti with no possibility of changing them back, I have to reboot my PC each time.

I am using Avast but it doesn't do anything I believe, there are no notifications informing me of any action taken, not to mention this thing started happening just today and I've been playing for quite a while now. Also in the first case I couldn't launch the game, the file was gone before the game started and in the second it disappeared after I exited the game.

So.. anyone?

Its antivirus.

Today i updated zclient exe and forgot to send it to microsoft, will do tomorrow.