I expect to be wrong. But I have an idea.
When that warning comes up, does it solicit any type of download?
If so, don't initiate a back-door into your computer via opting for a solution to a bogus pop-up.
I learned that lesson the hard way.
Please use the handy dandy reporting form available in your member centre:
Report Malware so that SkepticOverlord is alerted and can have a look.
Remember to describe the problem in detail.