Lengthy Samples

hi everyone! I recorded some noise that I was going to use as a sample in renoise. I had 3 samples, each about a minute long that I would trigger around a few meaures after each other. inevitably, this will work fine for awhile, but after I have worked on the song for a few minutes, the noise samples will no longer trigger correctly. I assume this is because they are relatively lengthy and large files. does anyone know a way to fix this problem or have any of you experienced a similar problem? ^_^