Alright, so I noticed I was having problems with all my games, not just River City Ranson Ex.
I did what you asked and checked the micro SD for errors. I had put cheats onto the micro SD and a lot of them had errors. I reformatted the micro SD once again & this time did not put any cheats onto the micro SD. I checked for errors again & there are no errors.
I tried a couple games and they work fine now and save fine as well.
However, when I now try to play River City Ransom Ex, it freezes on the "Loading Creavting Sav File" screen and I cannot play the game at all.
I powered off, checked the microSD for errors again & the River City Ransom Ex 8kb save file was not valid & it was deleted.
I tried playing it again & have the same freezing issue.
Any idea why the game won't play at all now?