My 2011 iMac is still a great machine. I use it in my computer lab as my main computer. I upgraded RAM and I boot from an external SSD — both upgrades dramatically increased performance. I have kept it up to date on updates. But now when I try to use either "About this Mac" or "System Information" they do not work. "About this Mac" does nothing, and trying to launch "System Information" gets me an error message of "The application “System Information” can’t be opened."
Any ideas? Thanks!