What do you mean corrupt? You'll need to be more specific if you want a clear answer. Did avast allow you to see the specific issue?
If I had to speculate about what you are saying. I would bet avast is flagging the site accidentally. Its pretty easy to get flagged by avast and then requires the webmaster contacting them about the false positive to get it removed. Its kinda work to figure out what caused the false positive in the first place and can be something as silly as a poorly coded webpage. I went to the CBSA link and at first glance nothing really shady stands out. They may be on shared hosting with another site that caused this server to be flagged.