Gateway IP Monitor is tested and working on windows 7 x64, so something else its happening here. To know what, we need extra information thru evenlog. To do that, we go to Start and write on search box "Event". The first result will be "Event Viewer", here an screenshot for your guide:
Inside Event Viewer, from the left tree we go to Windows Log/System.
You should see under "level" column an Error, clicking on it you should check if it referes to Gateway Ip Monitor, and then pleas share the error with us so we can see what the problem could be. Here a second screenshot for guidance:
I'm looking forward to your reply to assit you more.