Built project is being flagged as a virus

I am in the final stages of a project I've been working on for a while, but just before release I've been noticing that my project has started being detected as a virus and my anti-virus scans the .exe before it is launched for the first time. It was also flagged as possibly dangerous on my girlfriend's PC.

This did not used to happen.

If I create a blank project and build it, the .exe does not get flagged as a virus. If I upload the .exe or the Data files of the project that is being flagged as dangerous to Virus Total there are no viruses found.

I have absolutely no idea what to do. I have scanned my computer with AVG but as I post this I'll be downloading something such as Search & Destroy to just double check.

Has anybody else had this problem? The last thing I want is people downloading my game and asking why it's been flagged as a virus.