Hi Jaime...
Although I'm not sure of the reason why but your page, upon accessing, is infected with what my AV Program (Avira) has called "HTML/Infected.WebPage.Gen" Avast is correct in this detection. Information on this trojan is available here...
http://www.avira.com/en/threats/section/fulldetails/id_vir/3684/html_infected.webpage.gen.htmlEDIT: Ok, this isn't the brightest thing I've ever done, but I didn't know about the tools the others have listed below.

First, did you write this HTML code on your own system? What is the content and purpose of your site? What editing software did you use. Have you performed a full system scan with avast?
Avast does have the ability to exclude individual files from main and real time scanning but you have to know where to go in the program.
Best Regards...