Today a new kaspersky antivirus update detects ace_fcs.dll as Trojan-Dropper.Win32.Sysn.bgyq. I believe this is a false-positive, however if you are finding you are getting the missing ace dll error and can't get on the servers do the following.
Open settings:
Select Additional:
Threats and Exclusions:
Configure Exclusions:
Add a new exclusion:
Select the file you wish to exclude from antivirus scanning. I chose my entire steam folder, you can just do the .dll that is causing the issue. Ensure you have the object name set as Trojan-Dropper.Win32.Sysn.bgyq
Click add and you should be good to go.
Add the dll back to the @ACE folder, restart Kaspersky and you should be able to continue without having Kaspersky deleting the DLL.
Hope this helps
PFC Wardlaw