You are right to be concerned - however, I have also seen this happen with some AV systems (specifically, Avast)
The point is that the AV system doesn't think you're using SSL, and so they're trying to force you to use SSL - THEIR SSL - and that's not the way SSL works (actually, technically, SSL is dead - it's really TLS, but everyone still SAYS SSL even when they mean TLS)
So, yes - you're seeing a man-in-the-middle warning, and it won't work because that's one of the things SSL is SUPPOSED to protect you from!
To solve the issue, you need to find the cause...