Microsoft Natural Ergonomic Keyboard 4000 won't work on OS X El Capitan

For example, others said they no longer get an option in Security & Privacy to "Allow apps downloaded from anywhere" but my system, upgraded from yosemite, still shows me that option.

That's in Sierra. Though it's possible to enter a command in Terminal to make "Anywhere" show. But there's no need to do that. Any unsigned app can be run by right clicking on it and choosing Open. Just as it could before.

but I can't access your link

That's bizarre. I tried it from here right after posting to make sure it worked, and it did. But you already found it otherwise.

Luckily for me, though, your tips worked! I just rebooted and the keyboard's back to working great!

Bless you, Kurt.

Now that I've succeeded in restoring function, can I go back and reenable that System Integrity Protection again?

Yes, you can turn that back on now. In El Capitan, occasionally IntelliType will simply stop loading for no apparent reason. Then you need to disable SIP and install it again. Not sure if that still happens in Sierra. Hasn't been around long enough to determine long term behavior.

Personally, I just leave SIP off. I always keep two copies of my personal data on separate drives, a bootable clone of the day to day OS I'm using, and a second backup of that. In case of any nasty malware that may someday pop up, I can just clone a clean copy of the drive back.

I get the "Unauthorized" message as well. I guess this is the one you found: Getting IntelliType for MS keyboards or mice to load at startup

Yup, that's the topic. Can't figure out why the link I posted isn't working for others. I have no issue with it here. Hmm. 😕

Kurt, thanks for your help. However, it's not working for me. I've tried your tip to install intellitype in sierra 10.12.1, in order to be able to configure my microsoft keyboard and mouse.

I disable SIP, succesfully install microsoft desktop 8.2 (the OS tells me it will complete after reboot), reboot but when I look in the library/PreferencePanes folder, it's empty. searching for the files you mentioned also delivers nothing. Searching for "intellitype" or microsoft desktop. I'm not sure whether it has installed?

Do you have an idea what might be going wrong?

sorry, I was looking in the wrong place. Works perfectly!!

UPDATE: the recent macOS Sierra update broke this again, but repeating these steps has once again restored my awesome Microsoft Ergo keyboard's special functions, as before. Since this might be a repeat adventure, I'm printing the steps to do all this on actual paper, to save time next time it happens.

Thanks again, Kurt Lang!

Yes, that's been an issue since El Capitan. It's related to System Integrity Protection. If you install an OS update, Combo updater, or the entire OS over itself, it almost invariably disables IntelliType because the OS sees the .kext driver in the System folder, and such third party items are no longer supposed to be installed there. So if SIP is on, it gets disabled, and you have to temporarily disable SIP to install IntelliType again.

Ah, gotcha'! That's a good workaround. Just have to retrain your brain so you can do it without thinking so you simply go for those keys as readily as you do for Command+C without looking.

Kurt Lang's method solved this for me; thanks Kurt, amazing insight to get it all working.

..aaand it's gone. It stopped working again. It were 4 happy weeks 🙂