G4 Powerbook memory woes


So, I finally caved and went out and bought a stick of 512MB memory from Comp-USA (my g/f's sister works there... discount). Now, I was being careful and I didn't want to buy some crappy memory that probably wasn't going to work. And sitting in the display case convienently was a nice stick of 512MB 2700 DDR 3.5, like what is in the computer, and on the package, it says made for mac g4. so I was like sweet, that has to work! So I got home and I installed it and the mac tech guy that they have at comp usa said I can leave the old mem in if I want, so I did... and then the fun began... Computer starts crashing for no reason, safari, mail, all kinds of stuff just randomly crashes, and I see something I have never seen before on this computer! A screen comes up and says that I must restart my computer in like 5 languages... and it is all locked up. So I do... and then it happens again... so I am like ok, fine. I take out the old memory and just leave in the new stuff, in the slot that the stock memory was in, and it happens even more frequently... so I give up, take out the new memory and put the old memory back in, and what do you know, no more crashing, no more problems.. The memory is made my Centon, it says it is made for this computer, but yet it totally sucks! what should I do? Can I return it?
What memory should I buy instead?
its a faulty chip. you've just been unlucky. return it asap. i dont know which companies are better than others so i would just go for a direct swap. one bad chip doesnt mean they all are.
The memory that I have bought at crucial.com has always been good memory. However, this may have just been good luck for me.