Well, I did a quick search on www.google.com/linux
and found on the second page (at the top) that a broken pipe means that one process finished before another. For example, tar aborts before bzip finishes.
To quote the page I saw,
"There should have been another message before the broken pipe. Are you low on memory by any chance? Are your tar files more than 2GB? Those are the only things that come to mind."
Can you give more details of your problem, or this just a query?