I recently added a fresh install of 64 bit Windows 7 to my Win XP / Ubuntu dual boot system on a separate SSD. I did this because while AH3 works fine on 32 bit Windows XP, it does show some annoying graphical anomalies. Specifically, it can't handle all the trees and as you increase the range for rendering trees some of the ones in the foreground disappear. I suspect a resource issue. So I installed 64 bit Windows 7 Home Premium and it works fine; it actually gives a bit higher frame rate (DX9 version) and doesn't have the resource limitation problem with trees.
However, one thing is really annoying me: the Variance in Delay plot has a 1 second burp that appears like clockwork exactly every 70 seconds (see attached image). The burp is real as planes warp during that 1 second. The hardware is identical and the Windows 7 install is absolutely clean. Only AH3 and PingPlotter have been installed. I haven't even updated Windows 7 from the DVD install state (putting off dealing with the new "who knows what's in it" roll-up patches). The burp does not show up in Windows XP, so it has to have something to do with Windows 7, not with my router or Internet connection (or AH).
Does anyone have any ideas? Things I've tried that had no effect: turning off power management for the WiFi interface card and trying to update the cards drivers (said was newest version available) and turning off SuperFetch (which should not have been enabled in the install as it's an SSD). Note, Windows Update is off (well it's set for Off, but the process still runs because... who knows).