This thread may be out of date, but it scores high in web searches for a current issue: Windows Live Mesh changes the welcome screen resolution shortly after the screen comes up. It may have been because I was using a different resolution when I first installed Live Mesh.

I just modified the DWORD values in the following folder for "width" and "height" to match my native resolution:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Live Mesh\Remote Desktop\DisplayDevices\DEVICE0