I don't think it's the anti-virus - I tested a .scr with your .mfa and that was clear on Norton too. No threats found.
I think the .scr freezing our computers is a different issue and not a virus issue.
Hi guys, with build 292.27 the problem with antivirus Is fixed?
Update: this build, as well as the build 292.26, has a bug in the physics engine in collision detections with scaled objects, due to one of the optimizations we did. Here is a version of the Physics Engine object that should fix the problem if you can't wait for the next beta version: