Starting a month ago when I open Safari (6.1.6) on my mac Pro (OS 10.7.5) the window whooshs to the right and disappears. When I "Reset Safari" everything greys out and I have to force quit.

Thanks for the quick reply. After searching around a bit I found the source of the problem but not the reason why. For some reason having a second monitor (in my case a TV) hooked up to the Mac Pro with an HDMI cable causes this problem. When I disconnected the TV the problem went away. Some of my apps won't work in Yosemite so I can't go that route. I wish Apple had kept Safari separate from the OS as they had in the past so you could just update Safari and not everything else.