I took of all my AV programs, but still wouldn't work.
I also have a laptop which has the same problems.
And I have another installation of Windows 7 and it doesn't work with it either.
And there are numerous other people that have had problems with Fences not working on Win7 64-bit.
So I think it is a problem with the program, not necessarily my machine when so many others have experienced the same problems for the past 2-3 years.