I have had a very quick look at your link profile and it seems there are 2 major issues.
1. You anchor text profile is over optimised for commercial terms, this looks unnatural to Google and is usually what algorithmic updates such as Google Penguin look for to reduce a sites rankings.
2. A lot of your links seem to be forum profiles, this is an old and quite spammy way of building links to a site. These types of links used to work to gain rankings but with recent advancements and updates in Google these can actually harm your site.
I would recommend to look at all the links pointing to your site, look closely at what links are unnatural and attempt to get them removed. As well as this I would recommend submitting these unnatural links to the Google Disavow Tool in your Webmaster Tools account.
