YBOS has some bugs--in fact one was recently found and fixed by an expert. The odds are very good, however, that if you have a problem with YBOS, it is pilot error, and not a YBOS bug. Unless you are doing fancy I/O on new machines, you're not likely to be exercising code that hasn't been exercised literally millions of times already. Check your code for things like calling routines with arguments in the wrong order, or some of the standard YBOS bugs illustrated below.
This is a self-test exploring the most common YBOS bugs.