Microsoft Management Console problems -- MMC cannot open files

Greetings,
Hoping that someone can help me out.... Dell Inspirion desktop, win7 home premium, about 1-2 years old. Has been running ok until last week. Major symptom is screen stuck at 640x480. When I right click and try to change the resolution, I get long string of ::{26ee0688- blah blah.... as the dialog title, and in the box it says "windows cannot find same long string underneath... hit ok and another dialog box titled explorer.exe and inside it says windows cannot find ". make sure you typed the name correctly, and then try again. hit ok, tried again and same results.... this led to poking around in control panel. noticed that many items I clicked to open would not respond.... nothing. ex. personalization or display or system or troubleshooting... when i clicked device manager, got dialog titled microsoft management console, inside MMC cannot open the file c:\\windows\system32\devmgmt.msc. stuff about it may not exist, is not a console, or created by a later version of mmc.. or i don't have sufficient rights... tried administrative tools and it did come up, and opened an explorer view of files like component services, computer management etc. clicking all said same mmc cannot open file message.... Googled a bit and was led to attempting the sfc /scannow tool. Tried for several days and got the same message "windows resource protection, could not start the repair service"...hence my attempt in forums.. now, as I type this desperate plea I tried sfc again and..... sfc is now working!?!?! waiting for it to finish...---- am I on the right track? can someone point me to a thread or guidance on how best to continue to recover?? Many thanks!!

Do you have a system restore point from before this issue?

Thanks for the fast response... the sfc in progress was indeed run as sfc /scannow. It found errors, and said it fixed them and logged to a cbs file... ran it two more times, with no integrity violations found.... about recent changes, I cannot identify anything specific, except possible my daughter running a Nancy Drew game that normally lowers the resolution, but it has always come back to normal upteen times... I'm using the major geeks malware; avast, and comodo, no other firewalls turned on. I do use ccleaner to clean, and once in a while I've used the registry fixer.... I do have a restore point from before this issue, but the mmc problem won't let me run that tool... thanks yodel99

Wait!! I just went back to control panel (after successful sfc /scannow run), and it DOES open the different programs now, such as recovery, device manager and system... do you suggest using a restore point, or is there other evidence I might uncover to help going forward? thanks

Please forgive my excitement about running sfc.... I just tried to change the screen resolution and it worked! Everything "seems" back to normal.... but again, if you feel it would be good for me to run other diagnostics, I'd be happy and maybe help others in the forum. thanks yodel99

Sounds like system file checker fixed the issue.

You should try everything it wouldn't let you before to make sure everything is working.

Thanks so much for the support! May I beg one last question... as I was looking into using a system restore point, I see that there are protection settings for two drives, RECOVERY and OS Csystem). protection is OFF for recovery, and ON for c:, are these the proper settings? thanks again!