Help .aspx/ going to another page -- loosing sleep over this :)

Hi Everyone I am hoping someone can help me out. I have my pages setup as https://domain.com/about.aspx. My site works normal and everything is cool but I was not being indexed by Google. I checked a site and it confirmed I have a url error so when someone types in https://domain.com/about.aspx/ my site comes up with all the images missing but all the text there. Does anyone know why?? I am assuming the correct response should be a 404 or the aspx work. Hoping someone can help! Thanks T