Crazy Keyboard Issue

[Sen]

Hi All - I am currently using a late 2015 iMac which has been working well, and after typing some text the other night, all seemed fine - the following morning I went to log into online banking and received a login error - after a couple of further attempts I discovered that the letters/numbers being typed in were NOT what was being typed - some keys weren’t typing any thing, and some were typing 2 different letters simultaneously - my initial response was the keyboard [extended wired] must be faulty [the computer itself seemed be working well otherwise] I then tested the keyboard with my previous iMac and the same thing happened - so I thought that confirmed a keyboard fault, but I also have a spare keyboard which I tested on both macs, and the same issue was present [albeit with different keys affected] - I have tried absolutely everything, including resets and checking all settings correct - I have been on forums and tried everything suggested, to no avail - so basically I have 2 iMacs which were both working well, and 2 keyboards, which also were both working well - both macs seem to be fine in all other respects, but suddenly both keyboards respond as if gone haywire - I am now at a complete loss as to what to do about it - if anyone has any idea what could cause such a bizarre situation to arise, and can help, I would be eternally grateful, as it’s doing my head in.

 

[TonyAguila]

Hi All - I am currently using a late 2015 iMac which has been working well, and after typing some text the other night, all seemed fine - the following morning I went to log into online banking and received a login error - after a couple of further attempts I discovered that the letters/numbers being typed in were NOT what was being typed - some keys weren’t typing any thing, and some were typing 2 different letters simultaneously - my initial response was the keyboard [extended wired] must be faulty [the computer itself seemed be working well otherwise] I then tested the keyboard with my previous iMac and the same thing happened - so I thought that confirmed a keyboard fault, but I also have a spare keyboard which I tested on both macs, and the same issue was present [albeit with different keys affected] - I have tried absolutely everything, including resets and checking all settings correct - I have been on forums and tried everything suggested, to no avail - so basically I have 2 iMacs which were both working well, and 2 keyboards, which also were both working well - both macs seem to be fine in all other respects, but suddenly both keyboards respond as if gone haywire - I am now at a complete loss as to what to do about it - if anyone has any idea what could cause such a bizarre situation to arise, and can help, I would be eternally grateful, as it’s doing my head in.

Try first to reboot in Safe Mode. It might be connected with a running process. What version of macOS is running? Maybe a reinstall will fix the problem. If both Macs are running the same system version, and if the other data are also similar, that could explain the similar behaviors.

I try to keep a copy of the macOS installer for the system version I’m running. In a lot of cases, when weird behaviors develop, a quick reinstallation of macOS fixes the problem. It never hurts, but make sure you have reliable backups, just in case.