Don't use any of these characters: * ? < > | " : \ / (asterisk, question mark, left and right-angle bracket, pipe, straight quotation marks, colon, BACKSLASH, FORWARD SLASH). Also, don't add the .qdf extension; Quicken does that for you.
After adding accounts, see if you are experiencing the same problems in this test file.
Eric Laser said: Thanks for your help. I'll try that. Unfortunately, when I back up my files, I usually overwrite the previous one.