A few weeks ago when I tried to invoke a standard scan, I received a msg from Windows that it couldn’t run and would notify me when a solution was reached. And now, when I open CCleaner, the initial window appears and then closes.
Have you tried reinstalling CCleaner?
You can get an installer here: Download CCleaner builds | CCleaner Portable, Slim, and more
What version of Windows are you running?
Did Windows say in that message just why it “couldn’t run” CCleaner?