Need help on loading samples from compact flash card

I bought a Lexar 4GB compact flash card and loaded a sample pack from the Akai sight that I bought. I load the samples and when I go to record a song it right away goes from record to overlay. Then sometimes it will play things back all over the place like it lost the samples. It works fine with the card that came with the unit, and reords fine. can someone please help me?

The MPC1000 supports cards up to 2 gb. I think that's the problem.