A common reason for this type of issue, is that you are using code which has been used in the past by known viruses, even if you believe that you are not using it for "bad" reasons. API calls like key loggers, or automatic mouse-clickers. Do you use any API calls, or 3rd party libraries in any way, shape or form? The chance that all your projects are using such code is low, so the other option is that you actually have a virus on your machine.