I upgraded a 2011 MBP and 2011 MBA to 10.7.2 The MBP seems to be working fine. The MBA has a problem after it goes to "sleep". When I hit a key to wakeup the MBA, the graphics are all messed up. When I move the cursor on the trackpad, there are little block graphics that "clear" the screen area as I move around. I have to clear an area around my "logon ID", then click and enter my password and it starts OK. Seems fine after I am back into OSX. I also notice I now have a Guest Account Icon next to my regular logon. Suggestions on what I can do to fix these? Particularly the graphics redraw problem? Thanks in advance..