problems resizing buffer

I'm working on a looper patch using buffer~/groove~/poke~. The initial buffer size is 30 sec, and the first loop tells groove~/poke~ which part of buffer~ to use for overdubbing. I've been trying to change the patch so that the first loop will resize the buffer~ instead of just telling which part of buffer~ to use, but i can't seem to find a way to do this. I thought i had found a solution when i started using "crop", but the problems started when i cleared the buffer created a new loop. Before doing this i initialized the buffer size with a "size" message. When i started looping again the sound was heavily distorted, some kind of digital distortion. It seems like sending the a crop message to buffer~ object and setting buffer length back messes up my patch. Any idea why this happens?