I have had this same issue since early beta test. Sad to say that my solution will probably not be the best for everyone but here goes. Since I have a lot of extra hard drive space over the 4 hard drives in my computer I went with a radical solution. I installed a clean install of Windows 7 on a separate hard disk. I only installed the microsoft updates for Win7 and updated my Nvidia drivers. There is literally nothing installed on that windows except GW2. It runs perfectly and I can stay connected for hours on end. So I dual boot at start up with my old 2+ year old windows 7 install and if playing GW2 I boot to my GW2 window 7 install. Like I said its pretty radical but I would say that this proves that something on my other install is causing connection issues.