10.11.4 weird issues (login and language)

Firstly, you should install all available software and firmware updates if you haven't already done so. Once you've done that, please generate and post an EtreCheck report.

 

I'm not surprised you're experiencing problems considering how much junk you've installed on your Mac.

Try the following:

1. Use Malwarebytes Anti-malware to remove the all of the intrusive/malicious software from your Mac.
2. Uninstall the following software:
   • Java
   • LogMeIn
   • PACE iLok (and whatever software installed it)
3. If the issue persists, then uninstall all non-essential software, one piece at a time.

Although, if I were you, then I'd perform a clean reinstallation of OS X and start again.

 

Did you recover from a Time Machine backup? I'm wondering how, in two weeks, you could have all that stuff installed on your "new" iMac.

 

When you upgrade through the years via Time Machine, applications and third-party background processes can get passed on to the newer operating system even if they're not compatible with the newer system. Their presence can be disruptive. I have seen this happen over and over with clients.

You have to get rid of what isn't compatible. How? Two ways:

1. Examine your system carefully (via such things as the Etrecheck report) and do the research on everything in there. Get rid of what you have discovered is incompatible. If you don't know what you're doing, this method can bring on a world of pain.
2. Start from scratch with a new system and reinstall what you need.

I wouldn't expect anyone to be able to troubleshoot what's going on with your system via a web forum. Just start with the second option and be prepared to have to update some of the software that you have been using in previous versions of Mac OS X.