When waking up my MacBook Pro, the external monitor unpredictably displays "snow flakes" I can't seem to pinpoint a specific cause for this, but sometimes when I wake my MBP the external screen gets fuzzy, like a TV with no reception, but I can faintly see my desktop behind the noise. If I sleep the display again (with hot corners) and wake it up again it's fine. Anyone know how to fix this?
I have had the same problem with Maverick (in clamshell mode) / external monitor (Samsung SyncMaster 2443) when I lock my screen and use my bluetooth mouse or keyboard to wake up the computer. 

I was able to fix the problem in 2 ways:


open the lid, login and unplu, replug the external monitor (pretty annoying)
when the multicolor static shows, press CTRL+SHIFT+Eject as if to lock the computer again, then wake up the computer again and I now have the normal login screen as normal (not ideal but less disruptive solution).


I hope this helps !