I just upgraded my MacBook Pro 13" (Late 2009) from 2GB RAM to 8GB. The memory I installed is the Kingston Kit, KTA-MB1066K2/8G.
Ever since the upgrade, my MacBook freezes at unpredictable moments not long after I start using it. The moment it freezes, both displays show blue vertical lines, though it happened once without the lines.
Another thing that struck me was that without my 26" 1920 x 1200 external monitor hooked into the MacBook, this freezing hasn't happened thus far.
Also, I flipped one memory card with the original 1GB, resulting in a total of 5GB now. The freezing hasn't happened thus far.
Is anyone familiar with this faulty behaviour?
(Bonus question: is it really that bad to have a 1 and 4 GB card next to each other?)