"About This Mac" and System Profiler won't open
I have an iMac9,1 from 2009 that (as far as I remember) is running MacOS X Yosemite (ver. 10.10). At some point I noticed that the "About This Mac" menu item in the Apple Menu stopped working. I just get nothing if I choose that option. In addition, if I go to the Utilities dock icon and choose System Profiler, I just get a pop-up window with the error message "The application “System Profiler.app” can’t be opened.". So now I don't have the normal way to check what version of MacOS I have (or run a full System Profile).
A short while after I bought this iMac used, I used the Migration Assistant app to move files from my even older iBook G4 laptop to the iMac. I know the "About This Mac" and System Profiler app were working fine when I first got the iMac. But I didn't pay attention to whether they stopped working immediately after I migrated my files.
Furthermore, I recently looked at an error report that was generated by an app called "Android File Transfer" (which I downloaded when I was trying to get some photos off of an Android smartphone and onto the iMac). That error report included a line that said that my OS is: 10.11.6 (Build 15G21013). I don't recall ever doing anything to upgrade my OS from ver 10.10 to 10.11.
Incidentally, I checked the Macintosh HD/Applications/Utilities folder, and the System Profiler app is there. Doing a 'Get Info' on this file shows me that it's version 10.10.
I do NOT have any MacOS installation disks.
So here are my questions:
1) Is there another way to check exactly what version of MacOS I'm running?
2) Is there a way to get the "About This Mac" and System Profiler features working again? Or a way to download a new clean version of the System Profiler file from the internet?
3) Could Migration Assistant have done something to replace or corrupt the System Profiler app?
4) Could I have upgraded my OS from ver 10.10 to 10.11, and then that process initiated the problems with "About This Mac" and System Profiler?