I'm on Win 7 x64 and had a lot of junk installed. You name it, I probably had it. Just from the top of my head, things like: WebSphere Server, iis, MySQL Server, 3 different Visual Studio versions, bunch of versions of .NET frameworks. I got rid of everything and now I can run PCI ULLI at the lowest setting without a glitch. I even played an H.265 video at the same time and browsed the Internet and no dropouts!
The best would be to disconnect completely (like Gary always says), but I need a connection on that computer. Oh, I also shut off updates and disabled automatic reboot.
This may seem pretty obvious to most, but I just thought I would share my experience
-Tom