Immediately after I open Opera CCleaner reports "Browser Ceaned" Cleaner has cleaned Opera. Opera desktop does not even open up. All suggestions welcome.

OS Windows 10 - 64 bit

Opera has been my browser for 20 years (I used to pay for it!). When my Belgian bank started Internet banking many years ago, I signed on via Opera without problems. When the bank recently updated their software, I could still log on via Opera, but some operations became inoperative. I am now forced to do my banking via Firefox.
What do I need to do to get Opera to be as functional as Firefox? The main problem seems to be downloading of details; for instance: I can see account balances, but not the transactions within the account.
I use Windows 10, and Opera version 39.0.2256.71.

I use Window 10. The latest version of Opera, 34.0.2036.47 of 1/19/2016 does open and, without even being shown on the screen, shuts down immediately, as shown by the pop-up "CC Cleaner has cleaned Opera".The problem started after installing this latest version.
How can I get back to the previous version, .25?