How to solve HTTP Fake AV Redirect Request

Last time I didn't use secure cerfiticate. But from January, 2015, I have started to use secure cerfiticate.

However, yesterday my site was reported to have a threat Drive-By Downloads: HTTP Fake AV Redirect Request with a location. However, the location doesn't exist.

Please help me solve this problem! Thank you!

I have also attact the report:

[Edit: Removed hyperlink to a potentially malicious URL to conform with the Participation Guidelinesand Terms of Service]