exec command fails in php, works in the command line

I have two programs on two servers, and they both have similar problems. In each one, I use 'exec' to call a helper program. In one case, it is ecasound, which I use to resample an mp3. In the other, it is convert, which creates a thumbnail of a very large image the user has uploaded. In both cases, the exec command fails. Not all the time, but some times. In both cases, the command that is being called by exec will work fine at the command line. I assume that there is some memory / resource limit that is being breached when this happens, but I don't know what it is, or how to tell php to allow my programs to run. Any ideas? -Ernst Schoen-Rene New Disorder Records - ten years of something: Coming soon, new Power Struggle CD. * Free Email with 5 megs, no ads * Internet Radio Station - upload your music, we'll put it in rotation * 100's of CDs for sale * videos, message board, byofl http://www.newdisorder.com