Problems with Grimefighter

I purchased Grimefighter about two months ago but was never able to use it. As far as I’ve been able to get is downloading it, which it then tells me that upon restart it will begin it’s processes. The problem I am having is that it never gets past the boot-up process. After it says hit F2 for start-up it goes to a black screen where there is only a cursor in the top left of the monitor for a few seconds then nothing, though I can hear the computer working. I’ve waited for a while, hours and hours, but nothing ever comes of it. I have a Gateway 2012 model of some sort running Windows 7. Any help would be appreciated.

https://forum.avast.com/index.php?board=63.0