Avast! Only Malware Detection

For some reason Avast anti-virus has opted to block access to this website. Stating that it has blocked access to the website because of Malware at https://sitename.com.au/|>{gzip}. It also talks about the infection being: “HTML:Script-inf”.

Whats odd is that the website works on any internet device running Norton or Windows generic protection and presumably AVG etc… I checked for the basic signs of somebody screwing around with the website. Checked for any malware presence on the site or anything and nothing came up.

Nobody that I know of has accessed the site since it stopped working. Although some plugins are setup to update on their own.

Does anybody know what the issue is or could point me in the right direction?