This is what will sometimes appear on your screen.
For the past few weeks in using Illustrator CS5, it has come to my attention that a very consistent problem kept coming up, the perspective grid.
If you use the key command Shift + O to modify your art boards you may sometimes hit Shift + P instead, by doing so it will add a very intrusive grid on your screen. It’s not very clear how to remove this massive distraction at first glance, so here’s how to do it:
View > Perspective Grid > Hide Grid
Mac Keyboard Command:
Shift + Command + i
Windows Keyboard Command:
CTRL + Shift + i