crashing unless wait commands are used

A coworker has recently told me that Matlab keeps crashing when he runs his code unless he puts in wait commands thoughout it. The computer has 16gb of RAM and a i7 processor running Windows 7 64bit. The data sets are in the 4-10 million data point range. He mentions that he's filling up all the RAM doing this and that Matlab has a slight memory leak when he gets to about 10 million data points. I'm curious if this sounds reasonable. I don't have any code to show so I don't expect an exact answer, I'd just love to hear some opinions of if this sounds like potential matlab behavior or if there is something wrong with the computer's RAM.