System Error DSETUP .dll is missing from your computer.
 

Not sure what i did wrong here???

im having the same issue, probably ur anti-virus or something blocking it

So I was looking at this same thing. I have downloaded the patch files a few times just to make sure it wasn't corrupting. I can open the zip and see the dsetup.dll in the zip file. When I extract the files, it disappears. I checked my anti-virus and it is quarantining the file for some reason. I am unable to use the old dsetup.dll from the last patch.
Which leads me to the question, with all the other people having problems, is it possible the zip is corrupt or that this dll is actually virus infected?
Edit: False alarm... I really need to read sticky posts about false positive flags on antivirues.

funny thing is i don't have an antivirus.

fixed. Somehow I still had some bitdefender files and was giving me this issue. I was able to delete all of bitdefender in safe mode and now everything works.

I disabled my antivire (Avira) and still cant unpack the Dsetup.dll.

found a way to put the file on a exception list. works now

I dont have anti virus and still missing. so i download the game again installed it works cool now i wannted to install the patch V49 but now it says its a virus???? and cant download it .. and i played with np for around 4 hours ago and download V49 last night but ofc i delete the zip Doh .. what to do ?

i was having the same problem.. funny though the game was working earlier today, but tonight it had the dsetup error

i copied dsetup from the patch before this one,,, now it works :)

I spoke too soon, I also had to do this as i was getting virus warning:
copied from another person's post :

Posted this on another thread, but I had same problem this morning and fixed it through the following...

Launch 'Windows Security' setting -> click ' Virus & Threat Protection' -> click 'Protection history'. From there I found a 'Threat quarantined' entry for the dsetup.dll file. I clicked the drop-down action to 'Restore' the file and everything started working again.