MBP Mid 2009 - PC3 8500 1066MHz vs PC3 12800 1600MHz

so i have bought two 2GB SODIMM DDR3 PC3 12800 1600MHz to replace my 2gb PC3 8500 1066MHz rams. after installing, my MBP becomes extremely unstable. my apps keep crashing (especially safari when trying to run flash) and i can't even run games on bootcamp. could these be due to:

1. faulty ram

2. incompatible ram

3. both

thanks.