won't let my friends see site using domain name

[Smackie]

I setup a virtual host on xampp which works great but for some reason (i set up different domains) i give my friends one of my urls (ex: http://domainname.com) and it gives them a error yet on my end i see my site good.. but yet i can give them my ip and the folders to the site (ex: http://ip/domainfolder/index.php) and they can see it.. on the old version of xampp i use to have i never had a problem with.. I been using xampp for years btw.. so can anyone help me with my problem??

Thank you in advance
Smackie