Download
http://download.macromedia.com/pub/flashplayer/updaters/8/flash_player_update3_flash8_win.zip and install the "Install Flash Player 8 Plugin.msi"
Another good thing about this player package is you can open swf files outside of your browser window, you also might need this for the camera view and remote connection with the soon to be available "Shuttle remote" window.
Li, download Mach (v053) , cause in older versions of Mach/Flash we had a variable running lose in there,but the newer versions killed it.
I don't think that it's a Mach problem,since your computer slow's down when loading a web page normaly.
Scott, Are you using Mach3 Loader or Mach3mill? could you try loading the default Mach 1024,close down and reopen with a Flash screen. I noticed that the Gcode has a red font, I'm wondering if it has anything to do with a previous screen setup conflict.
The strange thing is it looks from the picture that part of the bottom door of the screen is outside of the Iframe,which makes me think that somehow the screen is loading into the tab window, the other strange thing is ,that part of the door should be masked...for some reason the PNG's and masking aren't working. Can you pull the tab window open? or what happens when you in-logate the windows width and shorten it's height, does more of the Flash screen appear.
One important thing if people are having any problems is that when the pop up window to chose your pot connection appears,you'll have to chose the "not to show this again" and reopen Mach. Will need to fix this.