Why does Quicken crash when manually adding downloaded account transactions?

After downloading bank account transactions and attempting to add those transactions to the subject account the software asks if I want to open a new account or add it to an existing account -- this request just started this month. I choose to add it to an existing account. The data file appears to be downloaded but then a couple of screens appear to attempt to open and then Quicken crashes. When I reopen Quicken and check the account the downloaded transaction data if there and the software behaves normally after that. I have checked the data file. It happens from a data file and data copy file.