I'm cautious to link to the subdomain from the main site. I did this before and droped 50% of traffic from the main site. Also, Google Webmaster Tools showed over 3000 incoming links from Hollywood Nose to the subdomain / forum. I'm assuming Google frowned on this and saw it as spam or something of that nature.
All I would want is link to the subdomain in the top nav bar of the main site. Is this safe? Will I get an overabundance of incoming links resulting in an SEO drop? Does anyone have any experience in this matter? Thank you.