This is a new one; even though my resolution is set to 1920x1080 in game, and has NEVER had this problem with the 32-bit client (for 2 years now), my monitor automatically changes the resolution to 800x600 immediately. This happens approximately 95% of the time. Sometimes the game launches in the correct resolution (just lucky I guess?)
The only way to fix this is to change the setting from Fullscreen to Windowed, back to Fullscreen again. I have to use an electron microscope against my monitor to see this setting.
Any ideas why this is happening would be appreciated.