After downloading and running the diagnostic tool, I'm still getting the error message of

"The file you specified cannot be opened. Make sure that it is not currently being used by another program or a read only file. The Windows error was 'The system cannot find the path specified.".

As another user said, I can click on OK dozens of times and it will eventually go away, but this is not ideal. I don't know if it's going to work! I moved our QB Desktop 2012 to a Win10 machine. Did I not move the files correctly? 

I then get a message of Either there is no default mail client or the current mail client cannot fulfill the messaging request." 

Please help me understand if I've moved this correctly to the new computer!