Might be an IP block, but malware found at the IP your domain is on has been closed or dead since 2012-02-26 19:15:56,
another incident of server abuse has been recorded in 2009, so incidents far in-between,
Report to avast as a false positive, I do not seeing much in the sourcecode or scanning with Zscaler and Sucuri’s,
and your IP is not in this list: http://isc.sans.edu/asdetailsascii.html?as=21844
You can report here: http://www.avast.com/contact-form.php?loadStyles
If indeed found to be falsely blocked, it could be lifted with a next avast update, so report and wait for eventual results.
Stay safe and secure with avast,