I got an error code 603 (2020 Business) when I tried to open last years return, but I have not installed it on any other computer. It is activeate don this computer, and I just used it about a month ago to check on some info in the return. Whatever Intuit needs for me to prove ownership I will be only to glad to provide. Also, I am the only person who uses this computer, (it's my business records computer) so what gives?
