Quicken crashes when trying to backup or validate

JTS1

I'm running the R53.52 HF1 version of Quicken Desktop Classic Business and Personal on Windows 11 Home. During a recent 1-step update, the program seemed to hang for a while. After a couple of attempts, I was able to finish the update but some of the updated accounts had been duplicated twice so they each appeared 3 times in my account list. I was able to just delete the duplicate accounts, but now when I try to backup or validate my data file the program crashes - no error message, it just closes. I've been able to restore an old data file and an old backup data file but they still crash when I try to backup or validate. I restarted the program and Windows. I've now uninstalled and reinstalled Quicken but I'm getting the same results. Any ideas?