How do I delete this error code that I get each time I start my laptop? http://"c/Program%20Files/Mozilla%20Firefox/firefox.exe%22%20-new-window%20https://mail.yahoo.com/

Each time I power up my laptop I want my page to go straight to my Yahoo Mail. It does do that but it also tries to open another page that errors out. I think its because there's a 'c in the address and the file can't be found. I don't know how that filename got written into the Start Up Program and I can't find it to remove it. Please tell me like a First Grader how to remove this error message. http://"c/Program%20Files/Mozilla%20Firefox/firefox.exe%22%20-new-window%20https://mail.yahoo.com/ It says it cannot open the page. Thank you for any help you can offer. [redacted email from public]