i just received 8gb DDR3 1333MHz ram off amazon for $50. when i installed it into my 13inch mid 2010 macbook pro, it would freeze when starting up. What i have tried so far. 1)i replaced my apple stock 4gb(2gb x 2) of ram and the computer worked fine 2)i put one 4gb stick and a stock 2gb stick in and it worked fine 3)did the same thing as in #2 but used the other 4gb stick is anyone else having this problem? thanks for your help.