If you assume there is a single error and the application crashes in different places, it might be a dangling pointer. Accessing an already freed piece of memory will give you rubbish values (probably a segfault in most cases), they will be seemingly randomly overwritten as the application creates and destroys variables and does memory operations. This could be as easy as a missing malloc or a free too much.
However, I wouldn't bother to debug the app at all if first attempts don't reveal the source of the problem. If an application crashes in ten different places, when the app uses seemingly unrelated data, the author surely has written tons and tons of code without ever compiling and testing it in the process and now is helpless because one error led to another. I would politely ask the app's programmer to have an intercourse with himself, and after he's done, to rewrite the faulty code from scratch, compiling and testing every few lines.
